A circle has an area of 12. If the radius is increased by a factor of 2, what is the new area of the circle?

A=12. A=π*r^2 (area of a circle)

π*r^2=12

r*2:

π * (r*2) ^2 = π*r^2*4. Here you can see that the calculation is exactly the same as above except from the Factor 4. This Shows that the area is four times bigger than before: 12*4