Question

What is the exact area of a circle having diameter 4 in.?

Answer 1

The exact area is 12.56 in.

First, consider the formula for the area of a circle, which is A=πr². The radius is half of the diameter, so if the diameter is 4 the radius is 2.

A=πr²
A=π2²
A=π4
A=3.14*4
A=12.56

Answer 2

r = d/2 = 4/2 = 2 in

A = π r^2 = π (2)^2 = 4π

answer
4π in^2