Some Applications of Trigonometry
CH09 Question Bank
CBSE_CH09_QUESTION_BANK
Grade 10
Question:
As an observer walks towards the foot of a tower (staying on the same horizontal line), the angle of elevation of the top of the tower:
Increases
Decreases
Remains the same
Becomes zero
Step-by-Step Solution
Key Concept: As horizontal distance decreases while height stays fixed, the angle whose tangent is height/distance must increase.
Since $\tan\theta=\dfrac{h}{d}$ and $h$ is fixed, decreasing $d$ (moving closer) increases $\tan\theta$, hence $\theta$ increases. [1.0 Mark]
Correct Answer: Increases
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