$P_{ABCD}=7800c{m}^2$

$\left|\angle EOF\right|=\left|\angle GOH\right|={150}^o$ $\left|\angle EOF\right|=\left|\angle GOH\right|={150}^o$

|OE|=|OF|=650mm=65cm

|OG|=|OH|=650mm-450mm=200mm=20cm

$P_{EGHF}=\frac{{150}^o}{{360}^o}\left({65}^2\Pi -{20}^2\Pi \right)\approx \frac{5}{12}\left(4225\cdot 3-400\cdot 3\right)=$ $\frac{5}{12}\left(12675-1200\right)=\frac{5}{12}\cdot 11475=4781,25c{m}^2$

$\frac{4781,25}{7800}\approx 0,6$

Odp. Wycieraczka czyści około 0,6 szyby.