Sample Problem

Cut 2 small circles of a radius of 2cm from a big circle with a radius of 4.5 cm. What is the area of the remaining shaded figure? The answer can be expressed in the form aπ. Find a, in decimal notation.

A =


The large circle has an area of 4.52 × π and the smaller circles have a combined area of 22 × π × 2. Thus the shaded region has an area of

4.52 × π - 22 × π × 2 = 12.25π cm2.