Find the area of the figure below, composed of a rectanlge with two semicircles removed.
Area of figure = Area of rectangle - 2 (Area of semicircle)
Two semicircle of the same radius, say r, has the same area as a circle with that radius r.
Notice that the area of a circle with diameter d is \(\dfrac{\pi d^2}{4}\).
Area of figure
= Area of rectangle - (Area of circle with diameter 6)
= \(15(6) - \dfrac{\pi \cdot 6^2}{4}\)
= \(90 - 9\pi\)
\(\approx 61.7\)