An observer 30 m away from the base of a building finds the angle of elevation of its top to be 30°. He then walks towards the building until the angle of elevation becomes 45°. How far (in m) did he walk?
Class 10Heights and DistancesTrigonometry
A30−103
B30+103
C103
D203
Step-by-Step Solution
Height h=30 tan 30=330=103. For 45°: tan 45=d2h⇒d2=h=103. Walked = 30 - 10 3 m.
Answer: A) 30−103
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