Question

3. A bridge across a river. makes an angle of 60° with the river bank. If the length of the bridge across the river is 120 m, what is the width of the river? ​

Answer 1

A bridge across a river makes an angle of 60° with the river bank. If the length of the bridge across the river is 120 m, 103.2m is the width of the river.

Given,

Angle = 60°

Length of river= 120m

To find,

width of river,

Concept to be used,

Pythagoras theorem,

Since, it is given that length of river is 120m and angle made by bridge with river is 60°.

$sin 60^{0} = \frac{width}{120}\\ \\\frac{\sqrt{3} }{2} = \frac{width}{120}\\ \\120(0.86) = width\\\\103.2 = width$

Therefore, a bridge across a river makes an angle of 60° with the river bank. If the length of the bridge across the river is 120 m, 103.2m is the width of the river.