An umbrella has 8 ribs which are equally spaced (see Fig. 12.13). Assuming umbrella to be a flat circle of radius 45 cm, find the area between the two consecutive ribs of the umbrella.
There are 8 ribs in the given umbrella. The area between two consecutive ribs is subtending
= 45oat the centre of the assumed flat circle
Area between two consecutive ribs of circle =
* 
r2
= 
* 
* (45)2
= 
* 2025
= 
cm2
21