Question

Mahmoud is working out the height, h metres, of a tower

BT which stands on level ground.

He measures the angle TAB as 25°.

He cannot measure the distance AB and so he walks 80 m

from A to C, where angle ACB = 18° and angle ABC = 90°.

Calculate

Answer 1

24.72 m

11.53 m

Explanation:

Horizontal distance AB can be obtained from △ABC

From trigonometry :

Sin18° = opposite / hypotenus

Sin18° = AB / 80

AB = 0.3090169 * 80

AB = 24.72 m

The height BT, of tower from △ABT

From trigonometry :

Tan25° = opposite / Adjacent

Tan25° = h / 24.72m

h = Tan25 * 24.72

h = 11.527

h = 11.53 m

Hence, height of tower BT = 11.53 m