Question

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

Answer 1

Since ribs are equally spaced. Therefore, Angle made by two consecutive ribs at the centre = `\frac { 360 }{ 8 } = 45º`

Thus,

Area between two consecutive ribs

= Area of a sector of a circle of radius 45 cm and sector angle 45º

`={ \frac{45}{360}\times \frac{22}{7}\times 45\times 45}`

`= \frac { 1 }{ 8 } × \frac { 22 }{ 7 } × 45× 45 cm^2 = 795.53 cm^2`