A support beam needs to be placed at a 28° angle of elevation so that the top meets a vertical beam 1.6 meters above the horizontal floor. The vertical beam meets the floor at a 90° angle.

Law of sines:

Approximately how far from the vertical beam should the lower end of the support beam be placed along the horizontal floor?

3.0 meters
3.4 meters
3.9 meters
4.4 meters

Respuesta :

The problem states that the law of sines needs to be used but the function tangent can also be used to solve this. Either way, the same answer will be obtained
Using the law of sines:
sin 28 / 1.6 = sin (180 - 28 - 90) / x
where x is the horizontal distance between the ends of the beams
Solving for x
x = 3.01 meters

The answer is
3.0 meters

You can use the law of sines along with the angle of elevation given to find out the length of the distance of the vertical beam from the lower end of the support beam(horizontally).

The distance between lower end of the support beam from the vertical beam along the horizontal floor is given by

Option A: 3.0 meters

What is law of sines?

For any triangle ABC, with side measures |BC| = a. |AC| = b. |AB| = c,

we have, by law of sines,

[tex]\dfrac{sin\angle A}{a} = \dfrac{sin\angle B}{b} = \dfrac{sin\angle C}{c}[/tex]

Remember that we took

[tex]\dfrac{\sin(angle)}{\text{length of the side opposite to that angle}}[/tex]

Using the law of sines, as referring in the figure attached below, we get:

[tex]\dfrac{\sin\angle C}{|AB|} = \dfrac{\sin\angle A}{|BC|}[/tex]

Since in a triangle, the sum of its angle is 180 degrees, thus,

[tex]\angle A + \angle B + \angle C = 180 ^\circ\\\angle A = 180 - 28 - 90 = 62^\circ[/tex]

Using the fact that |AB| = 1.6 meters and that angle C is of 28°, we get
[tex]\dfrac{\sin\angle C}{|AB|} = \dfrac{\sin\angle A}{|BC|}\\\\\dfrac{\sin28^\circ}{1.6} = \dfrac{\sin62^\circ}{|BC|}\\\\\text{Using sin calculator}\\\\\dfrac{0.469}{1.6} = \dfrac{0.8829}{|BC|}\\\\|BC| = \dfrac{0.8829 \times 1.6}{0.469} \approx 3.012 \approx 3 \: \rm meters[/tex]

Thus,

as length of BC = |BC| = 3 meters denote the horizontal length from the vertical beam and the lower end of the support beam, thus,

The distance between lower end of the support beam from the vertical beam along the horizontal floor is given by

Option A: 3.0 meters

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