Question

From a boat, 300 meter away from a vertical cliff, the angles of deviation of the top and the foot of a vertical pillar at the edge of the cliff are 55 and 54 respectively. Find the height of the pillar.

• A. 219.6 m
• B. 209.8 m
• C. 189.4 m
• D. 119.9 m

Answer 1

The correct option is A

219.6 m

$\frac{AB}{BC}$ $=tan\left({60}^{\circ }\right)$

So, AB = BC $\times$ tan ${60}^{\circ }$

$=300\times \sqrt{3}$

= 519.6 m

Now, $\frac{DB}{BC}$ = tan ${45}^{\circ }$

DB = BC tan ${45}^{\circ }$

DB = 300 $\times$ 1

DB = 300 m

Height of pillar = 519.6 m – 300 m

= 219.6 m