Question Statement :

In the figure, O and O’ are the centres of the bigger and smaller circles respectively and small circle touches the square ABCD at the mid-point of side AD. The radius of the bigger circle is equal to 15 cm and the side of the square ABCD is 18 cm. Find the radius of the smaller circle.

Type in your answer as a decimal number rounded off to two decimal places. For example, if your answer is 125.565 cm, type in 125.57