Height & Distance – Sun’s altitude from shadow ratio A vertical pole casts a shadow on level ground. If the length of the shadow is √3 times the height of the pole, what is the angle of elevation of the Sun (measured from the horizontal)?

Difficulty: Easy

Correct Answer: 30°

Explanation:


Introduction / Context:
Problems that connect a pole’s height and its shadow use right-triangle trigonometry on level ground. The angle of elevation θ of the Sun satisfies tan θ = (opposite)/(adjacent) = height/shadow. Here, the shadow is a known multiple of the height, so the triangle's ratio is fixed.


Given Data / Assumptions:

  • Pole is vertical; ground is horizontal.
  • Shadow length = √3 × (pole height).
  • Angle of elevation θ is acute and measured from the horizontal.


Concept / Approach:
Let height = h and shadow = √3 h. Then tan θ = h/(√3 h) = 1/√3. The standard acute angle whose tangent is 1/√3 is 30°.


Step-by-Step Solution:

Let height = h > 0Shadow = √3 htan θ = height / shadow = h / (√3 h) = 1/√3Hence θ = 30°


Verification / Alternative check:
For θ = 30°, the 30°–60°–90° triangle has opposite:adjacent = 1:√3, matching the given shadow-to-height ratio.


Why Other Options Are Wrong:
60° gives tan = √3, not 1/√3. 90° is vertical Sun (shadow 0). 45° gives tan = 1, which requires equal height and shadow, not √3 times.


Common Pitfalls:
Inverting the ratio (taking shadow/height instead of height/shadow), or confusing 30° and 60° special-angle tangents.


Final Answer:
30°

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