If A is the area and C the circumference of a circle, which of the following is an expression for A in terms of C?

If A is the area and C the circumference of a circle, which of the following is an expression for A in terms of C?

A c2/4π

B c2/4π2

C 2c

D 2c2 √π

Solution

Correct Answer: Option A

a=4πr2 c=2 πr r=c/2 π now,a=4πr2 =π x ( c/2 π)2 = c2/4π