Question

In fig the boundary of shaded region consists of four semicircular arcs, two smallest being equal if diameter of the largst is $14cm$ and that of the smallest is $3.5cm$. calculate the area of the shaded region. [Use $\pi =\frac{22}{7}$]

Answer 1

Area of smallest circle $=\frac{\pi }{2}\times {\left(\frac{3.5}{2}\right)}^2$

Area of outer small circle$=\pi \times (3.5{)}^2$

Area of bigger circle$=\pi (7{)}^2$

Area of shaded reason$=\pi [49-2{\left(\frac{3.5}{2}\right)}^2+(3.5{)}^2]$

$=\pi [61.25-6.125]=55.125$

$=173.25$.