Height from angle of elevation at a known horizontal distance From a point on level ground 50 m from the tower base, the angle of elevation to the tower's top is 30°. What is the tower's height?
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A50 √3 m
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B50 m √3
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C75 √3 m
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D75 m √3
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ENone of these
Answer
Correct Answer: None of these
Explanation
Introduction / Context:This is a direct tan relation in a right triangle. Angle of elevation θ at horizontal distance d gives height h = d * tan θ. Correctly evaluating tan 30° and simplifying radicals is all that is required.
Given Data / Assumptions:
- Horizontal distance d = 50 m.
- Angle of elevation θ = 30°.
- Level ground, vertical tower.
Concept / Approach:h = d * tan θ = 50 * tan 30° = 50 * (1/√3) = 50/√3 m. If rationalized, h = (50√3)/3 m ≈ 28.87 m. Check options for an exact match in form or value.
Step-by-Step Solution:
tan 30° = 1/√3h = 50 / √3 m = (50√3)/3 mVerification / Alternative check:Numerical value: (50√3)/3 ≈ 28.867 m. The provided options list only multiples of √3 like 50√3 m, 75√3 m, etc., none equivalent to 50/√3 m.
Why Other Options Are Wrong:All listed values represent heights far larger than 50/√3 m or in a mismatched form. None equals 50/√3 m.
Common Pitfalls:Using sin instead of tan, or flipping the ratio (taking h/50 = √3 instead of 1/√3). Also note the option formatting: “50 √3 m” is not the same as “50/√3 m.”
Final Answer:None of these