Question
The angle of elevation of the top of a building from a
point on the ground is 60°. After walking 20 meters towards the building, the angle of elevation becomes 75°. Find the initial distance from the point on the ground to the building.Solution
Let the height of the building be h meters, and the initial distance from the point on the ground to the building be d. From the first observation: tan(60°) = h/d, so h = d√3. From the second observation: tan(75°) = h/(d - 20). 2+√3= d√3/(d - 20)  d = 10(√3+2) meters. Correct option: c
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