Question

In the diagram, the radius of the outer circle is 2x cm and the radius of the inside circle is 6 cm. The area of the shaded region is 160π cm2. What is the value of x? Enter your answer in the box.

x =

Answer 1

7

Explanation:

It right

Answer 2

let's find the area of the outer circle and the inside circle
the inside's circle area
A= π x 6²=36π
the outer's
A' = π x 4x²= 4πx²
A'-A=4πx²- 36π=160πcm² equivalent to x²- 9=40, so x²=49 implies x =sqrt(49)=7, x=7