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

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

B) 4π cm2; 16π cm2; NO 

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