Question

From the top of a hill 30 m above a river the angles of depression of the banks of a river are 47° and 57° respectively. What is the width of the river? 6.5 m 8.5 m 7.5 m 0 9.5m

Answer 1

Ответ:

8,493≈8,5 м

Пошаговое объяснение:

Ширина реки КВ=СВ-СК.

∠САВ=90°-57°=33° ,  ∠САК=90°-47°=43°

ΔАВС , tg33°=CВ\30  , СВ=30*tg33°≈30*0.6494≈19,482

ΔАКС , tg43°=CК\30  , СК =30*tg43°≈30*0.9325≈27,975

КВ=27,975-19,482=8,493.