From the top of a cliff 25 m high the angle of elevation of a tower is found to be equal to the angle of depression of the foot of the tower. The height of the tower is
(a) 25 m
(b) 50 m
(c) 75 m
(d) 100 m
Given that: height of cliff is m and angle of elevation of the tower is equal to angle of depression of foot of the tower that is.
Now, the given situation can be represented as,
Here, D is the top of cliff and BE is the tower.
Let $C E=h, A B=x$. Then, $A B=D C=x$
Here, we have to find the height of the tower BE.
So, we use trigonometric ratios.
In a triangle ABD,
$\Rightarrow \tan \theta=\frac{A D}{A B}$
$\Rightarrow \tan \theta=\frac{25}{x}$..............(1)
Again in a triangle,
$\tan \theta=\frac{C E}{C D}$
$\Rightarrow \tan \theta=\frac{h}{x}$
$\Rightarrow \frac{25}{x}=\frac{h}{x}$ $[$ Using (1) $]$
$\Rightarrow h=25$
Thus, height of the tower = BE = BC + CE = (25 + 25) m = 50 m
Hence, the correct option is .