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2023

Mathematics

JAMB

The angle of elevation and depression of the top and bottom of another building, measured from the top of a 24 m tall building, is 30° and 60°, respectively. Determine the second building's height.

A.

24 m

B.

32√3m

C.

24√3

D.

32 m

Correct Answer: 32 m

Explanation

The height of the second building H = h + 24 tan θ = opp/adj tan 30° = h/x ⟹3√3 = h/x ⟹x = √3 = 3h ⟹x = 3h/√3 ....(i) tan 60° = 24/x ⟹√3 = 24x ⟹x√3 = 24 ⟹x = 24/√3 ....(ii) Equate equation (i) and (ii) ⟹3h/√3 = 24/√3 ⟹ 3h = 24 ⟹h = 24/3 = 8m ∴The height of the second building = 8 + 24 = 32m

The height of the second building H = h + 24 tan θ = opp/adj tan 30° = h/x ⟹3√3 = h/x ⟹x = √3 = 3h ⟹x = 3h/√3 ....(i) tan 60° = 24/x ⟹√3 = 24x ⟹x√3 = 24 ⟹x = 24/√3 ....(ii) Equate equation (i) and (ii) ⟹3h/√3 = 24/√3 ⟹ 3h = 24 ⟹h = 24/3 = 8m ∴The height of the second building = 8 + 24 = 32m
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