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The angle of elevation of the top of a lighthouse 60 m high, from two points on the ground on its opposite sides are 45° and 60°. What is the distance between these two points?

  • A.104.6 m
  • B.94.6 m
  • C.84.6 m
  • D.74.6 m

Answer: B

The points are on opposite sides, so the lighthouse foot lies between them and the two distances add.

\[ d_{45} = \frac{60}{\tan 45^{\circ}} = 60 \text{ m} \]

\[ d_{60} = \frac{60}{\tan 60^{\circ}} = \frac{60}{\sqrt{3}} = 20\sqrt{3} = 34.64 \text{ m} \]

\[ 60 + 34.64 = 94.64 \approx 94.6 \text{ m} \]

The larger angle yields the shorter distance: the steeper you must look, the closer you stand.

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