Answer: 529.675 cm² is swept clean.
Step-by-step explanation:
The formula for determining the length of an arc is expressed as
Length of arc = θ/360 × πr²
Where
θ represents the central angle.
r represents the radius of the circle.
π is a constant whose value is 3.14
Considering the bigger sector,
Radius = length of blade = 21 cm
θ = 150 degrees
Therefore,
Area = 150/360 × 3.14 × 21² = 576.975 cm²
Considering the smaller sector,
Radius = 6 cm
θ = 150 degrees
Therefore,
Area = 150/360 × 3.14 × 6² = 47.1 cm²
The area of the windscreen that is swept clean is
Area of bigger sector - area of smaller sector. It becomes
576.975 - 47.1 = 529.675 cm²
