Circumference Problems

Circumference Problems Circumference problems are the problems in which we need to calculate the circumference of a circle. It is calculated by the formula: - 2 x pie x r. Here 2 and pie (= 22/7 or 3.14) are constants, hence they dont have any units. And r is the radius of circle which is generally measured in metre (m) or centimetre (cm). Since the unit of circumference depends upon the radius so the unit of circumference is m or cm This can be understood by the detailed examples, which are shown below:- Example 1:- Find the Circumference of circle when diameter is 7000 cm. Solution:- Given the diameter of circle, d is 7000 cm. So the radius of circle is (radius is always half of the diameter), r = 7000/2 = 7000/2 3500 cm. Now circumference of circle = 2 x pie x r Therefore Circumference of circle, C = 2 x 22/7 x 3500 So C = 22000 cm. Hence the circumference of circle = 22000 cm. Example 2:- Find the Circumference of circle when diameter is 42 cm. Solution:- Given the diameter of circle, d is 42 cm. So the radius of circle is, r = d/2 = 42/2 = 21 cm. Now circumference of circle = 2 x pie x r Therefore Circumference of circle, C = 2 x 22/7 x 21 So C = 132 cm. Hence the circumference of circle = 132 cm.