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Two buildings are 100 metres apart. Building 1 is shorter than Building 2. From the edge of the roof of Building 1 closest to Building 2, the angle of elevation to the top of Building 2 is 25.0∘. From that same point, the angle of depression to the bottom of Building 2 is 30.0∘. Determine the height of Building 2 to the nearest metre.

User Chen Xie
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1 Answer

3 votes

Answer:

height of building 2 ≈ 104 m(nearest metre)

Explanation:

The angle of elevation from the top of the shorter building to the top of the taller building is 25°.The angle of depression from the top of the shorter building to the base of the taller building is 30°. The height of building 2 (taller building) is the sum of the height of building 1 plus the height from the roof of building 1 where the angle of elevation was measured to the topmost layer of building 2.

The height of building 1 can be calculated using the tangential properties of the right angle triangle formed. The adjacent side is 100 m while the opposite side is the height of building 1.

tan 30° = opposite/adjacent

tan 30° = height of building 1/100

height of building 1 = 100 tan 30°

height of building 1 = 100 × 0.57735026919

height of building 1 = 57.735026919

height of building 1 = 57.74 m

The angle of elevation from the top of building 1 to the top of building 2 forms a right angle triangle .

using tangential ratio

tan 25° = opposite/adjacent

tan 25° = height from the top of building 1 to the topmost layer of building 2/100

height from the top of building 1 to the topmost layer of building 2 = 100 tan 25°

height from the top of building 1 to the topmost layer of building 2 = 100 × 0.46630765815

height from the top of building 1 to the topmost layer of building 2 = 46.6307658155

height from the top of building 1 to the topmost layer of building 2 = 46.63 m

Height of building 2 = 46.63 + 57.74 = 104.37 m

height of building 2 ≈ 104 m

User Ritika
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