Question

The radius of a circle of area and circumference is doubled, how do you find the new area of the circle in terms of A?

Answer 1

4A

Explanation:

Let's say the initial radius was 'r' and when doubled becomes 2r
Hence the first A = `pi`r^2
After doubling the radius,
Area = `pi`(2r)^2
= 4`pi`r^2
= 4A