Question

An umbrella has $8$ ribs which are equally spaced. Assuming umbrella to be a fat circle of radius $45cm$, find the area between the two consecutive ribs of the umbrella.

Answer 1

There are 8 ribs in umbrella The area between two consecutive ribs is subtending $\frac{{360}^0}{8}={45}^{\circ }$ at the center of assumed flat circle

Area between two consecutive ribs of circle

$=\frac{45}{360}\times \pi r^2$

$=\frac{1}{8}\times \frac{22}{7}\times (45{)}^2$

$=\frac{11}{28}\times 2025$

$=\frac{22275}{28}c{m}^2$