Question

A vertical pole (more than 100 m high) consists of two portions the lower being $\tan ^ { - 1 } \frac { 1 } { 2 }$ at a point in a horizontal plane through the foot of the pole and distance 40 ft. from it, then the height of the pole is

• A. 100 ft.
• B. 120 ft
• C. 150 ft.
• D. None of these

Answer 1

Answer: (B)

120 ft

Answer 2

Obviously from figure,$\tan \alpha = \frac { h } { 120 }$ ........(i)

$\tan \beta = \frac { 3 h } { 120 }$ ........(ii)

Therefore, $h = 120,40$

But $h = 40$ can not be taken according to the condition, therefore