Question

A palm tree is supported by two guy wires as shown in the diagram below. Which trig expression can be used to find the height on the tree where the top guy wire attaches if the base of the wire is four feet from the base of the tree? A sin (30° + 45°) B cos (75° – 45°) C tan (75° – 45°) D tan (30° + 45°)

Answer 1

D

Explanation:

Answer 2

D.
`tan(30^\circ+45^\circ)` is the correct answer.

Explanation:

The given situation can be represented as a figure attached in answer area.

B is the base of tree.

C is the base of wires.

A and D are the end of 2 wires supporting the tree.

`\angle DCB =45^\circ\\\angle ACB =75^\circ\\`

Here, we need to find the Height of the tree which is represented the by side AB.

and we are given that bases of wires and tree base are at a distance 4 ft.

i.e. side BC = 4 ft

If we look at the
`\triangle ABC`, we are given the base BC and the
`\angle ACB`, and the perpendicular is to be find out.

We can use trigonometric identity:

`tan\theta =(Perpendicular)/(Base)`

`tan 75^\circ = (AB)/(BC)\\\bold {tan (45+30)^\circ }= (AB)/(4)\\\Rightarrow AB = \bold {tan (45+30)^\circ } * 4 = 14.93\ ft`

Hence, D.
`tan(30^\circ+45^\circ)` is the correct answer.