A decorative badge is formed by removing a sector of angle 60° from a circular sheet…
MATHEMATICS · Multi-part · CBSE · Mathematics · Areas Related to Circles · Areas Related to Circles
Problem
A decorative badge is formed by removing a sector of angle 60° from a circular sheet of radius 12 cm and, from its centre, also removing a similar sector of the same angle from a smaller concentric circle of radius 6 cm, leaving a ring-shaped sector.
(i) Find the area of the ring-shaped sector.
(ii) Calculate the lengths of its outer curved edge and inner curved edge.
(iii) The ring sector is to be painted at a cost of ₹0.50 per cm2, and its two curved edges are to be bound with thread costing ₹2 per cm. Find the total cost of completing one badge.
Take π=722.