RRB Junior Engineer / DMS / CMA 2015 · Question 21 of 480

From a point on the bridge across a river the angle of depressions of the bank on the opposite side of the river are 60° and 45° respectively. If the bridge is at a height of 3 m from the bank, the width of the river is

Mathematics - Trigonometry

Aa. 2(V3 + 1)m
Bb. 3(v/3 + 1)m
Cc. 3 - V3 m
Dd. 3 + J3 mCorrect

Answer: D. d. 3 + J3 m

Explanation

Let A and Bare the points on the banks of river and D is the point on brige. D AC => AC = 4= = V3 m a/3 lnABCD,tan45°= — BC =, i = A BC => BC = 3 m .-.Width of river = AC + BC = (a/3 + 3) m

Source: Arihant RRB JE Solved Paper 26-Aug-2015 (3rd Shift), Q91–150 — published solved-paper compilation (Q1–90 technical not included in this source) · memory-based

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