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To estimate the height of a building, two students find the angle of elevation from a point (at ground levedown the street from the building to the top of the building is 30°. From a point that is 400 feet closer tothe building, the angle of elevation (at ground level) to the top of the building is 52°. If we assume thatthe street is level, use this information to estimate the height of the building.The height of the building isfeet.

Sagot :

Given:

ground to building top is 30 degrees.

Distance = 400 feet

The angle of elevation at is top of the building = 52 degrees.

Find-: Height of the building.

Sol:

For the triangle ABC

Perpendicular = Height

Base = x

Angle = 52

Use trigonometric formula:

[tex]\begin{gathered} \tan\theta=\frac{\text{ Perpendicular}}{\text{ Base}} \\ \\ \tan52=\frac{H}{x} \\ \\ 1.2799=\frac{H}{x} \\ \\ x=\frac{H}{1.2799} \end{gathered}[/tex]

For the triangle ABD is:

Perpendicular = Height

Base = x+400

Angle = 32

[tex]\begin{gathered} \tan\theta=\frac{\text{ Perpendicular}}{\text{ Base}} \\ \\ \tan32=\frac{H}{x+400} \\ \\ 0.6249=\frac{H}{x+400} \\ \\ \end{gathered}[/tex]

Put the value of "x" is:

[tex]\begin{gathered} 0.6249(x+400)=H \\ \\ 0.6249x+249.947=H \\ \\ 0.6249(\frac{H}{1.2799})+249.947=H \\ \\ 0.488H+249.947=H \\ \\ 0.512H=249.947 \\ \\ H=488.407 \\ \end{gathered}[/tex]

So the height of the building is: 488.407 feet

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