Two wipers

What A car has two wipers which do not overlap. Each wiper has a blade of length 21 cm, sweeping through an angle of 120°. Find the total area cleaned at each sweep of the blades.

Correct answer:

S =  923.6282 cm²

Step-by-step explanation:

$$\begin{gathered} r=21\text{cm} \\ \alpha =120{}^{\circ } \\ k=\frac{\alpha }{360}=\frac{120}{360}=\frac{1}{3}\doteq 0.3333 \\ {S}_1=\pi \cdot r^2=3.1416\cdot 21^2\doteq 1385.4424{\text{cm}}^2 \\ S=2\cdot k\cdot S_1=2\cdot 0.3333\cdot 1385.4424=923.6282{\text{cm}}^2 \end{gathered}$$

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