If you double the diameter of a circle what happens to the area?

Answer 1

By ratios.

Linear a:b

Area a^2:b^2

Volume a^3;b^3

If a = 1 Then b = pi(1)^2

Then if a = 2 Then b = pi(2)^2

Hence a = 2 b = 4pi

So if you double the diameter then you increase the area by 4 times.

Answer 2

It becomes 4 times as large. Here is a simple example:

A = πr2

For diameter 2, A = π

For diameter 4, A = 22 * π = 4π.