NECO 2022 · Paper 1 · Q42

Elevation, depression & bearings

The angle of elevation of the top $B$ of a wall from a point $A$ on the ground is $30^\circ$ . If $AB = 50$ m, how far is $A$ from the foot of the wall, correct to 2 significant figures?

Worked solution (try it first)

$AB$ is the hypotenuse and the distance to the foot of the wall is the side next to the $30^\circ$ angle, so use cosine.
Distance $= 50\cos 30^\circ$
$\approx 50 \times 0.8660$
$= 43.30$ m.
To 2 significant figures that is 43 m, option C.

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