The required area = shaded area in the figure = $\frac{1}{2}({5^2} – {3^2})\left( {\frac{\pi }{4} – \frac{\pi }{8}} \right)$
$ = \frac{1}{2} \times 16 \times \frac{\pi }{8} = \pi $ square unit.
The required area = shaded area in the figure = $\frac{1}{2}({5^2} – {3^2})\left( {\frac{\pi }{4} – \frac{\pi }{8}} \right)$
$ = \frac{1}{2} \times 16 \times \frac{\pi }{8} = \pi $ square unit.