Shadow equal to height: When the length of the shadow of a vertical pole equals the height of the pole on level ground, what is the angle of elevation of the light source?

Difficulty: Easy

Correct Answer: 45°

Explanation:

Introduction / Context:Relating a pole, its shadow, and the angle of elevation uses basic trigonometry: tan θ = opposite/adjacent = height/shadow length.

Given Data / Assumptions:

  • Height = shadow length.
  • Level ground; vertical pole.

Concept / Approach:tan θ = height/shadow = 1 → θ = 45°.

Step-by-Step Solution:

Let height = h and shadow = h.tan θ = h / h = 1 → θ = 45°.

Verification / Alternative check:In a 45°-45°-90° triangle, legs are equal; consistent with the condition.

Why Other Options Are Wrong:30° or 60° would give unequal legs (shadows √3 h or h/√3), not equal lengths.

Common Pitfalls:Using sine or cosine instead of tangent; misreading “shadow equals height”.

Final Answer:45°

More Questions from Height and Distance

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion