Question

An observer standing on a cliff 320 feet above the ocean measured angles of depression of the near and far sides of an island to be 16.5 and 10.5 respectively. How long is the island ?

Answer 1

Answer:

154.10 Feets

Step-by-step explanation:

Given the following :

Height (h) of cliff = 320 feet

Angle of depression of near side = 16.5°

Angle of depression of far side = 10.5°

Using trigonometry :

We can obtain x and y as shown in the attached picture :

Tanθ = opposite / Adjacent

Adjacent = height of cliff = 320 Feets

For the near side :

Tanθ = opposite / Adjacent

Tan (16.5°) = x / 320

0.2962134 = x / 320

x = 0.2962134 * 320

x = 94.788318 Feets

For the far side :

Tanθ = opposite / Adjacent

Tan (10.5°) = x / 320

0.1853390 = x / 320

x = 0.1853390 * 320

x = 59.308494 Feets

Length of island = (59.308494 + 94.788318) feet

= 154.10 Feets