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 220π cm2. What is the value of x? Enter your answer in the box.

Answer 1

The area of a circle is πr²
the outer circle area = π 4x²
the inside circle area = π.6²=36π
the outer circle area - the inside circle area = he shaded region
π 4x² - 36π =220π cm2 it implies x²-9 =55 and x²=64, and x =sqrt(64)=8
the value of x is 8