Question

What is circumference and area when diameter d=13.

Answer 1

⇒ 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 ) 

Answer 2

The circumference would be 40.8 and the area would be 132.7