Difficulty: Medium
Correct Answer: 2h/3
Explanation:
Introduction / Context:Two angles of depression from a higher point to two points on or above the ground allow expressing horizontal distance and relative verticals, yielding the unknown tower height as a function of h.
Given Data / Assumptions:
Concept / Approach:If horizontal distance from cliff foot to tower base is x, then tan 60° = h / x → x = h/√3. For the top, vertical drop is h - T (T = tower height). tan 30° = (h - T)/x → solve for T.
Step-by-Step Solution:
x = h / √3 from tan 60°.tan 30° = (h - T)/x = 1/√3.Thus h - T = x/√3 = (h/√3)/√3 = h/3.So T = h - h/3 = 2h/3.Verification / Alternative check:Insert T back: Top drop = h - 2h/3 = h/3 → tan 30° = (h/3)/(h/√3) = 1/√3 ✔️.
Why Other Options Are Wrong:h√3, 2h√3, h/3 mismatch the tangent relations; only 2h/3 satisfies both angles simultaneously.
Common Pitfalls:Confusing elevation with depression; misplacing T in h − T; forgetting that both rays share the same horizontal distance x.
Final Answer:2h/3
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