Question

Question 10
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.

Answer 1

Number of ribs in umbrella = 8
Radius of umbrella while flat = 45 cm
Area between the two consecutive ribs of the umbrella
= $\frac{Totalarea}{Numberofribs}$
$Totalarea=\pi r^2=\frac{22}{7}\times (45{)}^2=6364.29c{m}^2$
$\therefore$ Area between the two consecutive ribs
$=\frac{6364.29}{8}c{m}^2$ $=795.5c{m}^2$