⇒ Solutions
The distance around the outside of a circle that is closely related to this concept of perimeter. We call the perimeter of a circle the circumference.
Diameter is the distance across the circle through its center.
The radius (r) is the distance from the center to a point on the circle. The diameter is always twice the radius. It is named by the Greek letter ( π ).
Pi ( π) is approximately , or 3.14 rounded to two decimal places. We can write the following formula.
= C = ( π ) × d
In finding the circumference of a circle, you can use whichever approximation for π you choose. If you are using a calculator and want more accuracy, use the key. There is another useful formula for the circumference of a circle.
C = 2 × π × r
Calculations
By Formula
C = π × d
3.14 × 13
41 ( Rounded answer )