NECO 2004 Mathematics · Question 4
A man is 40m from the foot of a cliff of height 23m. Calculate the angle of elevation of the top of the cliff from the man
Options
- A.50° 54′
- B.35° 06′
- C.30° 00′
- D.290 90′
- E.29° 54′
Answer: E. 29° 54′
Explanation written with AI and checked against the answer key
Analyze the question: The man stands 40 m from the foot of the cliff (the adjacent side), and the cliff is 23 m high (the opposite side). We need the angle of elevation θ.
Concept: For a right-angled triangle, tan θ = opposite / adjacent (SOH-CAH-TOA).
Solution:
tan θ = 23 / 40 = 0.575
θ = tan⁻¹(0.575)
Checking nearby values:
- tan 30° = 0.5774, which is slightly above 0.575
- tan 29.9° ≈ 0.5750
So θ ≈ 29.9°.
Converting to degrees and minutes: 0.9° × 60 = 54′, so θ ≈ 29° 54′.
Checking the options:
- A (50° 54′): too large
- B (35° 06′): too large
- C (30° 00′): tan 30° = 0.5774, which is close but not exact
- D ("290 90′"): this is a misprint and not a valid angle
- E (29° 54′): matches our result
Answer: E. 29° 54′
Tip: In elevation questions, draw a quick right-angled triangle and label the sides. Height is opposite and distance on the ground is adjacent, so use tan. When two options are close (like 30° 00′ and 29° 54′), compute precisely on your calculator rather than rounding.
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