Question

Calculate the area of a circle with a radius of 2 cm and a circle with a radius of 4 cm. Leave your answers in terms of pi.

When the radius doubles, does the area of the circle double?
A) 4π cm2; 8π cm2; NO
B) 4π cm2; 16π cm2; NO
C) 4π cm2; 16π cm2; YES
D) 4π cm2; 8π cm2; YES

Answer 1

A = πr^2

area of a circle with a radius of 2 cm
A = π 2^2 = 4π cm^2

area of a circle with a radius of 4 cm
A = π 4^2 = 16π cm^2

if radius double then
area of a circle with a radius of 4 cm
A = π 4^2 = 16π cm^2

area of a circle with a radius of 8 cm
A = π 8^2 = 64π cm^2

So the area of the circle does NOT double

answer:
B) 4π cm2; 16π cm2; NO