Trigonometryhard · Past Paper
An aeroplane at altitude h observes two points on opposite sides of the river at angles α and β. Width of river?
Ah(cotα + cotβ)
Bh(tanα + tanβ)
Ch / (cotα + cotβ)
Dh(sinα + sinβ)
✓ Correct Answer: A — h(cotα + cotβ)
Distance 1 = h cot α, Distance 2 = h cot β. Total width = h(cot α + cot β).
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