Question

The angle between the ground at the top of a flag pole is 25o when the observer is at point A. The observer walks 10 m directly towards the flag pole to point B and the angle is now 40o. What is the height of the flag pole assume the observers eyes are 2 m above the ground?

Answer 1

12.4967 m

≈ 12.5 m

Explanation:

From the solution diagram attached, to find /AB/, we apply sine rule:

AB/Sin 140° =AD/Sin 15°

AB = 10/Sin 15° x Sin 140°

= 24.8372 m

To calculate the height of the pole we will calculate BC first. Using the right angle triangle ∠ABC, we have:

Sin ∅ = BC/AB

Sin 25° = BC/ 24.8372

BC = 24.8372 Sin 25°

= 10.4967 m

The height of the pole = BC + 2.0

= 10.4967 + 2.0

= 12.4967

≈ 12.5 m