Math Problem Statement

As shown in the figure below, Debra is standing 95 feet from the base of a leaning tree. The tree is growing at an angle of 86° with respect to the ground. The angle of elevation from where Debra is standing to the top of the tree is 37°. Find the length, x, of the tree. Round your answer to the nearest tenth of a foot.

Solution

This problem involves applying trigonometry, specifically the law of sines, to find the length of the tree.

From the image, we know:

  • The distance from the person to the tree's base is 95 feet.
  • The angle of elevation from the person to the top of the tree is 3737^\circ.
  • The tree is growing at an angle of 8686^\circ to the ground.

We are tasked with finding the length xx, the tree's height.

Solution:

The triangle involves three sides and angles, and we can use the Law of Sines, which is given by:

sinAa=sinBb=sinCc\frac{\sin A}{a} = \frac{\sin B}{b} = \frac{\sin C}{c}

Where:

  • AA, BB, and CC are the angles of the triangle,
  • aa, bb, and cc are the sides opposite those angles.

In this case:

  • A=37A = 37^\circ (angle of elevation),
  • B=86B = 86^\circ (tree's tilt angle),
  • C=180(37+86)=57C = 180^\circ - (37^\circ + 86^\circ) = 57^\circ (remaining angle).

Now applying the Law of Sines:

xsin(37)=95sin(57)\frac{x}{\sin(37^\circ)} = \frac{95}{\sin(57^\circ)}

Solving for xx:

x=95×sin(37)sin(57)x = \frac{95 \times \sin(37^\circ)}{\sin(57^\circ)}

Now calculate the sine values and solve:

x=95×0.60180.838757.170.838768.16feetx = \frac{95 \times 0.6018}{0.8387} \approx \frac{57.17}{0.8387} \approx 68.16 \, \text{feet}

So, the height of the tree is approximately 68.2 feet (rounded to the nearest tenth).

Would you like further details or clarifications on any part of this process?

Here are some related questions:

  1. What is the Law of Sines, and how is it applied in different triangle types?
  2. How do you handle cases where you cannot use the Law of Sines directly?
  3. What is the importance of significant figures in real-life calculations like this?
  4. How does the angle of elevation help in finding heights or distances?
  5. Can the Law of Cosines be used in this problem, and if so, how?

Tip: Double-check your angle sums when applying the Law of Sines or any triangle-based calculation to avoid mistakes.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Angle of Elevation
Law of Sines

Formulas

Law of Sines: sin(A)/a = sin(B)/b = sin(C)/c

Theorems

Law of Sines

Suitable Grade Level

Grades 10-12