Answer:
See below.
Step-by-step explanation:
Area of outer circle = π R^2
and area of the inner circle = π r^2 so the area of the ring
= π (R^2 - r^2) (Equation (1) ).
Consider the triangle OBC. We have, by Pythagoras, R^2 = r^2 + BC^2.
So BC^2 = R^2 - r^2.
Substituting for R^2 - r^2 in equation (1):
Area of the ring = π BC^2 as required.
