question_answer

A tower subtends an angle \[\alpha \]at a point A in the plane of its base and the angle of depression of the foot of the tower at a point l meters just above A is\[\beta \]. The height of the tower is

A) \[l\tan \beta \cot \alpha \]

B)        \[l\tan \alpha \cot \beta \]

C) \[l\tan \alpha \tan \beta \]

D) \[l\cot \alpha \cot \beta \]

Correct Answer: B

Solution :

[b] From figure, we can deduce \[H=l\tan \alpha \cot \beta .\]