Question

The radius of a circle of area A and circumference C is doubled.

a) find the new area of the circle in terms of A

b) find the new circumference of the circle in terms of C

Please explain.

Answer 1

A1 = pi (r1)^2
A2 = pi (2r1)^2

c1 = 2 pi (r1)
c2 = 2 pi (2 r1)

the rest is yours

Answer 2

I got the same answer but they told me that the answer does not depend on pi and r

Answer 3

You make the ratios A2/A1 and c2/c1 to answer the question as given.
you end up with (2 r1)^2/(r1)^2 and (2r1/r1) to simplify further.

Answer 4

thanks for the help!

Answer 5

You are quite welcome.