Trigonometrymedium · Past Paper
A person standing on the bank of a river observes the angle of elevation of a tree on the opposite bank as 60°. When he moves 40 m away, it becomes 30°. Width of river?
A20 m
B40 m
C20√3 m
D10√3 m
✓ Correct Answer: A — 20 m
h = x√3 = (x+40)/√3 => 3x = x+40 => x=20 m.
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