Stepwise
Start practisingPractise

JAMB 2015 · UTME · Q32

The angle of elevation of a building from a measuring instrument placed on the ground is 30∘30^\circ. If the building is 40 m40\text{ m} high, how far is the instrument from the foot of the building?

Worked solution (try it first)
  1. The height is opposite the 30∘30^\circ angle and the distance dd is adjacent, so tan⁡30∘=40d\tan30^\circ = \frac{40}{d}.
  2. Rearrange: d=40tan⁡30∘d = \frac{40}{\tan30^\circ}.
  3. Dividing by 13\frac{1}{\sqrt3} multiplies by 3\sqrt3: d=403d = 40\sqrt3 m, option D.

Report a problem with this question