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# PreCalc Need Help?

Suppose you need to find the height of a tall building. Standing 15 meters away from the base of the building, you aim a laser pointer at the closest part of the top of the building. You measure that the laser pointer is 7◦

tilted from pointing straight up. The laser pointer is held 2 meters above the ground. How tall is the building?

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- micatkieLv 65 days ago
Refer to the figure below.

Point A is the laser pointer, and point B is the closest part of the top of the building.

In ΔABC:

tan(∠BAC) = BC/AC

tan(90° - 7°) = BC/(15 m)

BC = 15 tan(83°) m

BC = 122 m

Height of the building

= (122 + 2) m

= 124 m

- JimLv 75 days ago
SOHCAHTOA so you want Tan

Tan 83 = Opp/15; Opp = 15 Tan 83 = 122.1651

Then add 2 m = 124 m

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