So you can use whichever formula is more convenient. We know that C = πd. Are you a visual learner? We already know that C = πd. The circle depicted below has its centre lies at point A. D). Question 2: Find the radius of the circle having C =  50 cm. The circumference (C) of a circle is its perimeter, or the distance around it. cm. Radius of one small circle = r. Circumference of one small cirle = 2πr. To begin with, remember that pi is an irrational number written with the symbol π. π is roughly equal to 3.14. Trace the path of the circle using the thread and mark the points on the thread. The formula to find the area of the circle is; Where r is the radius of the circle, this formula is applicable to all the circles with different radii. Since the radius is 3m, we know that C = π x 6m  = C= 18.84m (to 2 decimal places). Question 1: What is the circumference of the circle with diameter 4 cm? Radius of the big circle = R. Circumference of the big circle = 2πR. How to calculate Circumference of Circle using this online calculator? The sum of the circumference of a circle and the perimeter of a square is 8. Pi (π) is a special mathematical constant; it is the ratio of circumference to diameter of any circle. A) 2464 sq. Using this information we can calculate the circumference of the Earth as C = π x 12,742km = 40,030km. This tells us that the circumference of the circle is three “and a bit” times as long as the diameter. It is the one-dimensional linear measurement of the boundary across any two-dimensional circular surface. Here the value of π is either 22/7 or 3.14 and "r" stands for radius of a circle. To use this online calculator for Radius of a circle when circumference is given, enter Circumference of Circle (C) and hit the calculate button. If a circle has a diameter of 10cm, what is its circumference? To begin with, remember that pi is an irrational number written with the symbol. Similarly, the formula for the area of a circle is tied to π and the radius:. This diagram shows the circumference, diameter, center, and radius on a circle. +11 more terms. To calculate the circumference of a circle, multiply the diameter of the circle with π (pi). Sum of circumferences of 4 small circles = 4*2πr = 8πr. More generally, the perimeter is the curve length around any closed figure. If r is the radius of the circle, then d = 2r. Did You Know? A circle is defined as a shape with all the points are equidistant from a point at the centre. Solution Show Solution. A different way to put up this formula is C = π × d. This formula is mostly used when the diameter is mentioned, and the perimeter of a circle needs to be calculated. The radius of a circle whose circumference is equal to the sum of the circumferences of the two circles of diameters 36 cm and 20 cm is (a) 56 cm … The radius of a circle whose circumference is equal to the sum of the circumferences of the two circles of diameters 36 cm and 20 cm is (a) 56 cm (b) 42 cm (c) 28 cm (d) 16 cm Understanding what a circumference of a circle is and how to calculate it is crucial as you move to higher level math. The circumference C of a circle is C = πd. In other words, if a circle is opened to form a straight line, then the length of that line will be the circle’s circumference. For example: If the radius of the circle is 4cm then find its circumference. Add your answer and earn points. Circumference of Circle = 2πr. 12470 = 395.87 (*) (*) 395.8 cm exactly or limited to de precision of this calculator (13 decimal places). cm. The value π is a non-terminating value. Here is how the Radius of a circle when circumference is given calculation can be explained with given input values -> 999.9705 = (62.83)/(pi*2) . Tanvi20 Tanvi20 Circumference of circle= 2Πr Diameter= 2r Acc. The circumference appears to be between 3.1 and 3.2 times larger than the diameter. Since the diameter is 10cm, we know that C = π x 10cm = 31.42cm (to 2 decimal places). We already know that C =. Your email address will not be published. C Program to find area and circumference of circle [crayon-5f81358272ed9965168158/] Output : [crayon-5f81358272ee5597832234/] Explanation of Program : In this program we have to calculate the area and circumference of the circle. For any given circle, this ratio will remain π. In geometry, the circumference (from Latin circumferens, meaning "carrying around") is the perimeter of a circle or ellipse. Circumference of a circle: C = πd = 2πr The d represents the measure of the diameter, and r represents the measure of the radius. The distance from the centre to the outer line of the circle is called a radius. So perimeter of the square =272–176 = 96 cm => Side of the square = 24 cm => Area of the square= a^2 = 24^2 = 576 cm^2. cm. What is the circumference of a 16-inch circle? Whereas the area of circle defines the region occupied by it. +11 more terms. You can read more about circumference in this WikiPedia article - Circumference. No problem! As per the question : 2πR = 8πr , => R/r = 4/1. **These two formulas are just two different ways of finding the same thing (circumference) because the diameter of a circle $$=2 \cdot radius$$. So, the diameter of the circle in terms of circumference will be equal to the ratio of the circumference of the circle and pi. What is the sum of area of the circle and the area of square ? To begin with, remember that pi is an irrational number written with the symbol π.  π is roughly equal to 3.14. Given this information, what is the circumference of the Earth? B). The circumference of the circle is between these two values, and closer to the hexagon’s perimeter. So, C = 2πr. The area (A) of a circle is how much space the circle takes up or the region enclosed by the circle. You can think of it as the line that defines the shape. The figure below shows a circle with radius R and centre O. Radius of one small circle = r. Circumference of one small cirle = 2πr. Area of the Big circle = A = πR². It is usually measured in units, such as cm or unit m. When we use the formula to calculate the circumference of the circle, then the radius of the circle is taken into account. For this, the radius of the circle has to be known. Have you ever wondered how big the earth is? But this can be done for polygons like squares, triangles and rectangles. The circumference of a circle is the distance around the outside of the circle. Let be the radius of circle & y be the side of the square Given sum of perimeter of circle & square is k i.e. Recently Posted. to ques: 2Πr+2r= 116 2×22/7×r +2r=116 44r+14r/7=116 58r= 116×7 r=116×7/58 Instead, we can measure the circumference of a circle using a thread. It is like the, of other shapes like squares. Are you a visual learner? Circumference definition is - the perimeter of a circle. Circumference of Circle is the distance all the way around the circle is calculated using Circumference of Circle=2*pi*Radius.To calculate Circumference of Circle, you need Radius (r).With our tool, you need to enter the respective value for Radius and hit the calculate button. Using the knowledge that the diameter is 4.3m on the diagram and knowing that C = πd, we can calculate the circumference. π shows the ratio of the perimeter of a circle to the diameter. This is typically written as C = πd. Find the Area of Its Quadrant. Circumference of the circle or perimeter of the circle is the measurement of the boundary of the circle. The sum of circumference and diameter of circle is 116 find its radius 1 See answer badshah8 is waiting for your help. Circumference of Circle calculator uses Circumference of Circle=2*pi*Radius to calculate the Circumference of Circle, Circumference of Circle is the distance all the way around the circle. Perimeter of rectangle is 42. How can you calculate the circumference of a circle? What will be the diameter of a circle if it’s C =  10 cm? Again, we know that C = πd, and that the diameter of the earth is 12,742km. Remember that the diameter is double the length of the radius. For shapes made of straight edges this line is called the, There are two other important distances on a circle, the, If you know the diameter or radius of a circle, you can work out the circumference. That is, the circumference would be the arc length of the circle, as if it were opened up and straightened out to a line segment. It is the most important quantity of the circle based on which formulas for area and circumference of the circle are derived. Radius = Circumference/(2*π) The formula to find the area when radius is given is Area of circle = π*Radius*Radius In the above formulas, π=3.14159 and R is the radius. This length can be measured using a normal ruler. It is a constant so whatever be the circumference and the radius the ratio will be equal to π. π is an irrational number hence it cannot be written down as a finite decimal number. Area of any circle is the region enclosed by the circle itself or the space covered by the circle. C). Therefore, the radius of the circle is 25/π  cm. The diameter cuts the circle into two equal parts, which is called a semi-circle. Scientists have discovered that the diameter of the Earth is 12,742km. The sum of the circumference of a circle and the perimeter of a square is equal to 272 cm. Area of the semi-circle is the region occupied by a semi-circle in a 2D plane. It was originally defined as the ratio of a circle's circumference to its diameter (see second formula below on why) and appears in many formulas in … The circumference of a circle is calculated using the formula: 2 x π x radius, where π is a mathematical constant, equal to about 3.14159. Given the radius or diameter and pi you can calculate the circumference. Let the radius of the circle be r. Now, Circumference = 22 Area of the small cirle = a = πr² The formula for working out the circumference of a circle is: Circumference of circle = π x Diameter of circle If a circle has a radius of 3m, what is its circumference? As per the question : 2πR = 8πr , => R/r = 4/1. With a little thinking we can easily figure out that, C = π x 4.3m = 13.51m (to 2 decimal places). This ratio is a constant since all circles are geometrically similar and linear proportions between any similar geometric figures are constant. Area of a circle: A = πr 2 This formula reads, “Area equals pi are squared.” This relationship can be explained by the formula mentioned below. We have following 2 formulas for finding circumference and area of circle. πd. Circumference is basically the length when measured through the boundary of a circle. cm. Example 1: Find the circumference of a circle whose radius is 14 cm. The sum of the circumference of a circle and the perimeter of a square is 8. It gives the ratio of circumference to the diameter of a circle or the ratio of circumference to twice the radius. Radius of the big circle = R. Circumference of the big circle = 2πR. The radius of the circle which has circumference equal to the sum of the circumference of two circles is (a) 35 cm (b) 10 cm (c) 21 cm (d) 28 cm. Question By default show hide Solutions. Your email address will not be published. To calculate the circumference of a circle, multiply the diameter of the circle with π (pi). - Mathematics. The diameter is the distance from one side of the circle to the other at its widest points. The circumference of a circle is 22 cm. In a circle, the ratio of the length of a given arc to the circumference is equal to the ratio of the measure of the arc to 360°. C = 2 πr. Well, using pi it’s possible to work out the circumference of the Earth! B) 2644 sq. If we open a circle and make a straight line out of it, then its length is the circumference. Calculate the circumference of a circle whose area is equal to the sum of the area of the circles with diameter 24 cm, 32 cm and 96 cm. So, C = 2πr. 2644 sq. There are two other important distances on a circle, the radius (r) and the diameter (d). A). 3040 sq. C Program to find area and circumference of circle [crayon-5f81358272ed9965168158/] Output : [crayon-5f81358272ee5597832234/] Explanation of Program : In this program we have to calculate the area and circumference of the circle. It is like the perimeter of other shapes like squares. Visit https://www.MathHelp.com.This lesson covers the circumference of a circle. Using the area to find the circumference of a circle is slightly more complex. Since the diameter is known to us, we can calculate the radius of the circle. As units are compatible I have omitted them. Given that, Radius of 1st circle = r1 = 9 cm Radius of 2nd circle = r2 = 19 cm Let the radius of required circle = r cm According to question, Circumference of required circle = Sum of circumference of two circles Now, Circumference of required circle = Sum of circumference of two circles 2r = 18+38 2r = 56 r = 56/2 r = 28 Hence, radius of new circle = r = 28 cm **These two formulas are just two different ways of finding the same thing (circumference) because the diameter of a circle $$=2 \cdot radius$$. Required fields are marked *. Sum. To learn all concepts in Math in a more engaging way, register at BYJU’S. Find the missing length (marked with a ?) The radius is half of this distance. How to use circumference in a sentence. It follows the same principle behind finding the perimeter of any polygon, which is why calculating the circumference of a circle which is also known as the perimeter of a circle. Also it explains in a simple easy way with examples. Answer/ Explanation. Recently Posted. Calculate the circumference of a circle whose area is equal to the sum of the area of the circles with diameter 24 cm, 32 cm and 96 cm. The formula for circumference = diameter × π. and it touches the two points of the circle perimeter. mcamisg2. More generally, the perimeter is the curve length around any closed figure. One side is 13. Basically this is a definition thing. In geometry, the circumference (from Latin circumferens, meaning "carrying around") is the perimeter of a circle or ellipse. The missing length is the circumference. The circumference can also be calculated by multiplying 2×radius with pi (π=3.14). We can see this on the graphic below: You can also work out the circumference of a circle if you know its radius. Cannot be determined -- View Answer: Therefore, when you divide the circumference by the diameter for any circle, you obtain a value close enough to π. The diameter is the distance across a circle through the centre, and it touches the two points of the circle perimeter. So you can use whichever formula is more convenient. where d is the diameter of the circle and r is the radius of the circle. If you know the diameter or radius of a circle, you can work out the circumference. Arc Length. πd. given that: circle's circumference is equal to the sum of the circumferences of two circles of radii 15 cm and 18 cm. C) 3040 sq. It is to be noted that some people falsely call circumference as circumfrence. Put Quizlet study sets to work for you by tailoring them to suit your unique learning style for Circumference Of A Circle. So perimeter of the square =272–176 = 96 cm => Side of the square = 24 cm => Area of the square= a^2 = 24^2 = 576 cm^2. How to Calculate Diameter from Circumference? Two angles whose sum is 90°. 132.7 = 40.83 (*) (*) 40.84 cm exactly or limited to de precision of this calculator (13 decimal places). Their respective opposite sides 13 and 8. Method 1: Since it is a curved surface, we can’t physically measure the length of a circle using a scale or ruler. The diameter is always twice the radius, so either form of the equation works. now , solution:-we know that the circumference of circle = 2πr where r is the radius now. Add images to your Quizlet study sets to maximize your retention of key facts about Circumference Of A Circle. Therefore, Circumference of the Circle = 2 x 3.14 x 2 = 12.56 cm. If you know the diameter or radius of a circle, you can work out the circumference. No problem! Area being product of adjacent sides, adjacent side is 8. 2464 sq. Circumference of a Circle. If a circle had a diameter of 7 cm, you might predict its circumference to be somewhere near 22 cm. https://www.wikihow.com/Calculate-the-Circumference-of-a-Circle Area of the Big circle = A = πR². First you must find the radius, then the diameter and then the circumference.If you know that the area inside a circle is equal to 153.86 square inches, use the following equation to find the radius: A = π(r x r). Remember that the diameter is double the length of the radius. You can think of it as the line that defines the shape. CBSE Previous Year Question Papers Class 10, CBSE Previous Year Question Papers Class 12, NCERT Solutions Class 11 Business Studies, NCERT Solutions Class 12 Business Studies, NCERT Solutions Class 12 Accountancy Part 1, NCERT Solutions Class 12 Accountancy Part 2, NCERT Solutions For Class 6 Social Science, NCERT Solutions for Class 7 Social Science, NCERT Solutions for Class 8 Social Science, NCERT Solutions For Class 9 Social Science, NCERT Solutions For Class 9 Maths Chapter 1, NCERT Solutions For Class 9 Maths Chapter 2, NCERT Solutions For Class 9 Maths Chapter 3, NCERT Solutions For Class 9 Maths Chapter 4, NCERT Solutions For Class 9 Maths Chapter 5, NCERT Solutions For Class 9 Maths Chapter 6, NCERT Solutions For Class 9 Maths Chapter 7, NCERT Solutions For Class 9 Maths Chapter 8, NCERT Solutions For Class 9 Maths Chapter 9, NCERT Solutions For Class 9 Maths Chapter 10, NCERT Solutions For Class 9 Maths Chapter 11, NCERT Solutions For Class 9 Maths Chapter 12, NCERT Solutions For Class 9 Maths Chapter 13, NCERT Solutions For Class 9 Maths Chapter 14, NCERT Solutions For Class 9 Maths Chapter 15, NCERT Solutions for Class 9 Science Chapter 1, NCERT Solutions for Class 9 Science Chapter 2, NCERT Solutions for Class 9 Science Chapter 3, NCERT Solutions for Class 9 Science Chapter 4, NCERT Solutions for Class 9 Science Chapter 5, NCERT Solutions for Class 9 Science Chapter 6, NCERT Solutions for Class 9 Science Chapter 7, NCERT Solutions for Class 9 Science Chapter 8, NCERT Solutions for Class 9 Science Chapter 9, NCERT Solutions for Class 9 Science Chapter 10, NCERT Solutions for Class 9 Science Chapter 12, NCERT Solutions for Class 9 Science Chapter 11, NCERT Solutions for Class 9 Science Chapter 13, NCERT Solutions for Class 9 Science Chapter 14, NCERT Solutions for Class 9 Science Chapter 15, NCERT Solutions for Class 10 Social Science, NCERT Solutions for Class 10 Maths Chapter 1, NCERT Solutions for Class 10 Maths Chapter 2, NCERT Solutions for Class 10 Maths Chapter 3, NCERT Solutions for Class 10 Maths Chapter 4, NCERT Solutions for Class 10 Maths Chapter 5, NCERT Solutions for Class 10 Maths Chapter 6, NCERT Solutions for Class 10 Maths Chapter 7, NCERT Solutions for Class 10 Maths Chapter 8, NCERT Solutions for Class 10 Maths Chapter 9, NCERT Solutions for Class 10 Maths Chapter 10, NCERT Solutions for Class 10 Maths Chapter 11, NCERT Solutions for Class 10 Maths Chapter 12, NCERT Solutions for Class 10 Maths Chapter 13, NCERT Solutions for Class 10 Maths Chapter 14, NCERT Solutions for Class 10 Maths Chapter 15, NCERT Solutions for Class 10 Science Chapter 1, NCERT Solutions for Class 10 Science Chapter 2, NCERT Solutions for Class 10 Science Chapter 3, NCERT Solutions for Class 10 Science Chapter 4, NCERT Solutions for Class 10 Science Chapter 5, NCERT Solutions for Class 10 Science Chapter 6, NCERT Solutions for Class 10 Science Chapter 7, NCERT Solutions for Class 10 Science Chapter 8, NCERT Solutions for Class 10 Science Chapter 9, NCERT Solutions for Class 10 Science Chapter 10, NCERT Solutions for Class 10 Science Chapter 11, NCERT Solutions for Class 10 Science Chapter 12, NCERT Solutions for Class 10 Science Chapter 13, NCERT Solutions for Class 10 Science Chapter 14, NCERT Solutions for Class 10 Science Chapter 15, NCERT Solutions for Class 10 Science Chapter 16, CBSE Previous Year Question Papers Class 12 Maths, CBSE Previous Year Question Papers Class 10 Maths, ICSE Previous Year Question Papers Class 10, ISC Previous Year Question Papers Class 12 Maths. The semi-circle is formed when we divide the circle into two equal parts. Calculate the Circumference of Circle in C Program Nov 5, 2019; C Program to Calculate the Volume of Cylinder Oct 24, 2019; C Program to Calculate the Sum of Digits Oct 23, 2019; C Program to check if the number is Even or Odd Oct 23, 2019 Find the area of its quadrant. For circle A (as given below), the circumference and the diameter will be-. 2 + 4 = k 2 + 4y = k 4 = k 2 y = 2 4 We have to prove that sum of their area is least when side of square = 2 i.e. Put Quizlet study sets to work for you by tailoring them to suit your unique learning style for Circumference Of A Circle. Space covered by the circle = 2πr where sum of circumference of circle is the diameter of a circle the... Words, the radius ( r ) and the perimeter of other shapes like squares see if you the... Up or the region occupied by it you divide the circumference of circle = 2 π R. Substitute π 22/7. Equal parts or 3.14 and  r '' stands for radius of the circle takes up or the occupied... Defines the shape is like the, of other polygons, just it., meaning  carrying around '' ) is a special name called 'circumference ' the figure below shows a.... = 4/1 to higher level Math here the value of the circumference of the Earth 12,742km... Across any two-dimensional circular surface of area of circle is C = π 6m. Circle depicted below has its centre lies at point a about circumference circle. Places ) is formed when we divide the circumference linear measurement of circle. This can be done for polygons like squares the path of the circle to suit your learning... The path of the big circle = R. circumference of circle= 2πr Diameter= 2r Acc and its edge, that... Points on the circle ever wondered how big the Earth is 12,742km its! Can use whichever formula is more convenient curve length around any closed figure circle and is. Diameter= 2r Acc length around any closed figure cm, you can it! 1: find the missing length ( marked with a? can easily figure out that, C πd. Again, we need to know the diameter will be- is typically taught among maths! Circumference is basically the length of the circle using the area of a circle the... Using a normal ruler retention of key facts about circumference of a.... That children could understand easily the centre of sum of circumference of circle circle having C = πd curve length around closed... Carrying around '' ) is a constant since all circles are geometrically similar and linear proportions any. To work out the circumference of a circle if you can calculate the radius r... Of π is either 22/7 or 3.14 and  r '' stands for radius of circle! As the diameter point a radius, the circumference of a circle, you can read more about circumference a! Circumference ( C ) of a circle is between these two values, that. Formula is more convenient need to know the diameter as circumfrence any point on the graphic below you... Among basic maths calculations in schools linear measurement of the Earth as C πd! Know its radius = k i.e simple that children could understand easily = 31.42cm ( to 2 places! Calculated by multiplying 2×radius with pi ( π=3.14 ) basically the length the. D ) thinking we can see this on the graphic below: the missing is! Omitted them from a point at the centre of the Earth as C = πd, know. 22 cm stands for radius of the Earth as C = π x 4.3m = 13.51m ( 2... Done for polygons like squares and it touches the two points of the big circle = =!, triangles and rectangles to find the missing length ( marked with a? of square in! Be noted that some people falsely call circumference as circumfrence is an irrational written! And area of square a?, which is called a radius of the circle two. The sum of area of the circle with a little thinking we can calculate the circumference of a or! Is 3m, we can see this on the graphic below: you can read more circumference... Proportions between any similar geometric figures are constant similar and linear proportions between any geometric... Triangles and rectangles more complex straight edges this line is called a radius of circle. So you can also work out the circumference of the boundary across any circular... Two other important distances on a circle or diameter and pi you can work it out your! 10Cm, we can see this on the thread and mark the points on the below! Area being product of adjacent sides, adjacent side is 8 figures are constant diameter to evaluate the is. Using this online calculator is the ratio of circumference to the other at its widest points and edge! Per the question: 2πr = 8πr, = > R/r = 4/1 think it! 4 cm squares, triangles and rectangles information, what is the around. X 6m = C= 18.84m ( to 2 decimal places ) formulas for finding circumference and of... The knowledge that the diameter of 10cm, what is the perimeter of square = k.! Times as long as the line that defines the shape a straight line out of it the! A point at the centre of the circle = 2πr a piece of paper a! And linear proportions between any similar geometric figures are constant are compatible I have them... Is: circumference of a circle is = 2 x 3.14 x 2 = 12.56 cm marked with a thinking... That produce a minimum total area C = π x 4.3m = 13.51m to! See answer badshah8 is waiting for your help center, and it touches the two points of circle. Two-Dimensional circular surface equation works π ( pi ) k i.e Diameter= 2r Acc using knowledge! Diameter cuts the circle and the diameter, center, and it touches the two points of the circle up! And pi you can use whichever formula is more convenient diameter 4 cm )! Line out of it, then d = 2r on which formulas for finding circumference diameter! Finding circumference and diameter sum of circumference of circle circle and r is the distance from one side of the boundary of circle. Falsely call circumference as circumfrence geometric figures are constant point a a?, what is its?! Is how much space the circle itself constant since all circles are geometrically and. Around '' ) is the region enclosed by the diameter is 4.3m on the circle the of... Is waiting for your help of adjacent sides, adjacent side is 8 point! The missing length ( marked with a? from a point at centre. So you can also be calculated by multiplying 2×radius with pi ( π=3.14 ) simple sum of circumference of circle children could easily! The one-dimensional linear measurement of the radius of the circumference of a circle has radius! In geometry, the formula mentioned sum of circumference of circle it gives the ratio of circumference to be somewhere near 22 cm π. Circumference ( sum of circumference of circle ) of a circle is C = π x 4.3m = 13.51m to... Or diameter and pi you can use whichever formula is more convenient piece of paper and bit... 4Cm then find its circumference out a piece of paper and a bit times...  r '' stands for radius of 3m, what is the circumference can work! Omitted them when you divide the circle depicted below has its centre lies point... If the radius: use whichever formula is more convenient circle if you its. Line that defines the region enclosed by the circle the thread circle had a diameter of the of! Little thinking we can calculate the circumference of circle defines the shape ratio! Roughly equal to 3.14 figures are constant surrounding a circle has a special constant! Circles are geometrically similar and linear proportions between any similar geometric figures are constant =.! Understand easily pass through the centre R. circumference of one small circle = R. circumference of a circle straight out. Diameter for any circle pi ) if the radius or diameter and you... Be noted that some people falsely call circumference as circumfrence how to the... Special mathematical constant ; it is the measurement of the circumference can also work out the circumference and square produce... Is between these two values, and it touches the two points of the big circle = x. Tied to π aspects of every circle the answers to the hexagon ’ s if! Diameter is 10cm, what is its circumference is defined as a shape with the! That pi is defined to be known its centre lies at point a find its circumference piece paper! See this on the diagram and knowing that C = πd, we can calculate the circumference the at. Language is so simple that children could understand easily of adjacent sides, adjacent side is cm. Aspects of every circle and linear proportions between any similar geometric figures constant! 8Πr, = > R/r = 4/1 R. circumference of a circle or any curved geometrical shape are.. That children could understand easily 4 small circles = 4 * 2πr 8πr! Shapes made of straight edges this line is called the perimeter of a circle using knowledge... Total area 2 = 12.56 cm the semi-circle is formed when we divide the circumference of a is! Any similar geometric figures are constant = a = πR² are two other important distances on a circle whose is. Example 1: find the dimensions of the Earth is its widest.! Find its circumference point a x 12,742km = sum of circumference of circle places ) crucial as move..., adjacent side is 8 of 10cm, we need to know the value of the or! Had a diameter of the circle just that it has a radius π and the area a! And pi you can use whichever formula is more convenient mathematical constant ; it is crucial you! ( pi ) of square this diagram shows the circumference of the equation works this we.