Question

The length of the shadow of a pole on level ground increases by 90m when the angle of elevation of the sun changes from 58° to 36°.Calcule the height of the pole

Answer 1

Answer: Approximately 119.76 meters

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Work Shown:

x = starting length of the shadow

y = height of the pole

tan(angle) = opposite/adjacent

tan(58) = y/x

1.6003345 = y/x

1.6003345x = y

x = y/1.6003345

x = (1/1.6003345)y

x = 0.62486936y

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When the angle changes, the adjacent side gets 90 meters longer

tan(angle) = opposite/adjacent

tan(36) = y/(x+90)

0.72654253 = y/(0.62486936y+90)

0.72654253(0.62486936y+90) = y

0.453994166y + 65.3888277 = y

65.3888277 = y-0.453994166y

65.3888277 = 0.546005834y

0.546005834y = 65.3888277

y = 65.3888277/0.546005834

y = 119.758478075162

y = 119.76

The height of the pole is about 119.76 meters.