Question

Can someone explain in the clearest way possible how to solve this problem and also does it involve using sin cos tan formulas?

A sailor judges the distance to a lighthouse by holding a ruler at arm's length and measuring the apparent height of the lighthouse. He knows that the lighthouse is actually 60 feet tall. If it appears to be 3 inches tall when the ruler is held 2 feet from his eye, how far away is it?

Answer 1

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Answer:

480 ft

Explanation:

The geometry involves two similar triangles. The ruler at arms length forms a triangle that has the opposite side 3 inches high and 24 inches (2 ft) away. That is, the distance from the eye to the ruler is 8 times the height of the ruler.

The triangle involving the lighthouse is similar. That is, the angles in it are the same, so the sides are proportional to those in the smaller (ruler) triangle. The distance to the lighthouse will be 8 times the height of the lighthouse, just as the distance to the ruler is 8 times the height of the ruler.

8 × 60 ft = 480 ft

The lighthouse is 480 feet away.