Question

What scale factor would make circle A the same size as circle B? 1) The radius of circle A is 2 cm and the radius of circle B is 12 cm. 2) The radius of circle A is 4 cm and the radius of circle B is 3 cm. 3) The diameter of circle A is 20 cm and the radius of circle B is 5 cm. 4) The radius of circle A is 4 cm and the diameter of circle B is 20 cm.

Answer 1

Explanation:

Area of circle = πr²

The scale factor A:B is as follow

1) 2:3

2) 16:9

3) 25:4

4) 4:25

Answer 2

Explanation:

1) area of B =
`\pi r^(2)` =
`\pi* 12^(2)` = 452.4 cm^2

area of A is =
`\pi r^(2)` =
`\pi* 2^(2)` = 12.6 cm^2

A will be scaled 452.4/12.6 = 36 times

using the same method we can say that

2) 0.56 times

3) 0.063 times

4) 6.25 times