Question

if the radius of a circles is increased by 30%, what per cent will it's area increase?​

Answer 1

Step-by-step explanation:

The new radius is 1.3r, so the new area is pi times 1.69r^2, so the percentage of increase in the area is 69%. The circumference of the circle is increased by 30%, and its area is increased by (1.3²-1²)×100 = 69%