WAEC Mathematics 2013 Paper

Concept:The angle of depression from the mast to the object is equal to the angle of elevation from the object to the mast.Use $\tan \theta = \frac{\text{opposite}}{\text{adjacent}}$ in the right-angled triangle formed.Explanation:Let the height of the mast be $h$ m.The object is $6$ m away from the base of the mast.So, $\tan 50^\circ = \frac{h}{6}$.Therefore, $h = 6 \tan 50^\circ$.Using $\tan 50^\circ \approx 1.19175$, we get $h \approx 6 \times 1.19175 = 7.1505$.Correct to 2 decimal places, $h = 7.15$ m.Answer:The height of the mast is $7.15$ m.Correct option: C.