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
  • A
    30°
  • B
    45°
  • C
    60°
  • D
    75°

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°

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