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

Answer 1

If you double the original radius, the area will become 4 times what it was.

The area of a circle is pi*r^2 = A. If our new radius (lets say x) is double (x=2r), we have pi*x^2 = pi*(2r)^2, which equals 4*pi*r^2 = 4A, or 4 times the original area.