Question

How do you calculate the area of a circle knowing the diameter and or the radius?

Answer 1

A=pi*r^2

Answer 2

A=pi*r^2
A=pi*(d/2)^2

Answer 3

r=d/2

Answer 4

\[2pi\int_{0}^{x}r\ dr\]

Answer 5

Thanks to all!!

Answer 6

To find the area, square the radius and then multiply by pi (~3.14).
For example, if the radius is 3, then 3*3 = 9, so 9*pi or ~28.27