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.
    A 10(тИЪ3-1) meters Correct Answer Incorrect Answer
    B 10(тИЪ3+1) meters Correct Answer Incorrect Answer
    C 10(тИЪ3+2) meters Correct Answer Incorrect Answer
    D 10(тИЪ3-2) meters Correct Answer Incorrect Answer

    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 = dтИЪ3. From the second observation: tan(75┬░) = h/(d - 20). 2+тИЪ3= dтИЪ3/(d - 20) ┬аd = 10(тИЪ3+2) meters. Correct option: c

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