Question

A car has two wipers which do not overlap. Each wiper has a blade of length $20cm$ sweeping through an angle of ${90}^o$. Find the total area cleaned at each sweep of the blades.[Use $\pi =3.14$]

• A. $888c{m}^2$
• B. $628c{m}^2$
• C. $228c{m}^2$
• D. $728c{m}^2$

Answer 1

Answer: (B)

$628c{m}^2$

Given

Radius $r=20cm$

Sweeping angle $\theta =90°$

Total area cleaned at each sweep of the blade$=2\times$ Area cleaned by one wiper

$=2\times$Area of sector with angle 90°

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

$=2\times \frac{90}{360}\times 3.14\times {20}^2$

$=628c{m}^2$