Question

In Fig. PSR, RTQ and PAQ are three semi-circles of diameters 10 cm, 3 cm and 7 cm respectively. Find the perimeter of the shaded region.

Answer 1

Radius of semicircle PSR = 10cm/2=5 cmRadius of semicircle PAQ =7cm/2=3.5 cmRadius of semicircle RTQ =3cm/2=1.5 cmHence perimeter of the shaded region =perimeter of semicircle PSR +perimeter of semicircle RTQ +perimeter of semicircle PAQ And we know that perimeter of a semicircle =π×rHence required perimeter = π×5 cm+π×1.5 cm +π×3.5 cm =3.14(5 cm+1.5 cm +3.5 cm)=3.14 ×10cm =31.4 cm