Question

The radius of circle A is r cm. The radius of circle B is twice the radius of circle A. What difference between the circumference of circle B and circle A (in cm)?​

Answer 1

9514 1404 393

Answer:

2πr cm

Explanation:

The circumference of a circle of radius r is ...

C = 2πr

For a radius of (r cm), the circumference is ...

A = 2π(r cm) = 2πr cm

For a radius of (2r cm), the circumference is ...

B = 2π(2r cm) = 4πr cm

Then the difference between the circumferences is ...

B -A = (4πr cm) -(2πr cm) = 2πr cm . . . . difference in circumference