Problem C

A Divided Circle

Two circles are said to be *concentric* if they have the same
centre.

In the diagram below, there are two concentric circles. The radius of the smaller circle is \(5\) cm. The portion inside the larger circle that is outside of the smaller circle is divided into eight congruent pieces that each have the same area as the smaller circle.

In terms of \(\pi\), what is the circumference of the larger circle?

**Theme: **Geometry & Measurement