Question 6

Mathematics Heights and Distances Hard

Angles of elevation of the top of a tower from three points (collinear) A, B and C on a road leading to the foot of the tower are 30°, 45° and 60° respectively. The ratio of AB and BC is

(A) \(\sqrt[]{3}:1\)
(B) \(\sqrt[]{3}:2\)
(C) \(1:2\)
(D) \(2:3\)
View Dynamic Solution & Explanation
Correct Solution: Option A

Step-by-step Solution:

Suppose the tower is \( DE \) of height \( h \), where point \( \mathbf{D} \) is on the ground. Then, \[ AD = \frac{h}{\tan 30^\circ} = h \sqrt{3}, \] \[ BD = \frac{h}{\tan 45^\circ} = h, \] \[ CD = \frac{h}{\tan 60^\circ} = \frac{h}{\sqrt{3}}. \] The ratio \[ \frac{AB}{BC} = \frac{h \sqrt{3} - h}{h - \frac{h}{\sqrt{3}}} = \frac{\sqrt{3}}{1}. \]