When shadow length equals height, find elevation: If the length of a pole’s shadow on level ground equals the pole’s height, what is the angle of elevation of the light source?
Aptitude
Height and Distance
Difficulty: Easy
Choose an option
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A30°
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B45°
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C60°
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D75°
Answer
Correct Answer: 45°
Explanation
Introduction / Context:Same principle as similar items: tan θ = height/shadow. Equal height and shadow implies tan θ = 1 and θ = 45°.
Given Data / Assumptions:Height = shadow; vertical pole; level ground.
Concept / Approach:Use tan θ = opposite/adjacent.
Step-by-Step Solution:
tan θ = h / h = 1 → θ = 45°.Verification / Alternative check:A 45°-45°-90° triangle has equal legs, matching the condition.
Why Other Options Are Wrong:30° and 60° correspond to √3 ratios, not equality; 75° would make a very short shadow.
Common Pitfalls:Using sine/cosine instead of tangent; misinterpreting which angle is asked (elevation, not depression).
Final Answer:45°