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


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