Math Problem Statement

A survey team is trying to estimate the height of a mountain above a level plain. From one point on the plain, the team observes that the angle of elevation to the top of the mountain is 24°. From a point 1,000 feet closer to the mountain along the plain, the team finds that the angle of elevation is 28°. How tall (in feet) is the mountain? Round to two decimal places.

Solution

To solve this problem, we can use trigonometry, specifically the tangent function, since it relates the angle of elevation to the height of the mountain and the distance from the observation point to the mountain.

Given information:

  1. First observation:

    • Angle of elevation, θ1=24\theta_1 = 24^\circ
    • Distance from the mountain = dd (unknown)
  2. Second observation:

    • Angle of elevation, θ2=28\theta_2 = 28^\circ
    • Distance from the mountain is d1000d - 1000 feet.
  3. The height of the mountain = hh (unknown, to be found).

Steps to solve:

  1. Set up equations based on the tangent function. For the first observation point: tan(24)=hd\tan(24^\circ) = \frac{h}{d} So, h=dtan(24)h = d \cdot \tan(24^\circ).

  2. For the second observation point (closer by 1000 feet): tan(28)=hd1000\tan(28^\circ) = \frac{h}{d - 1000} So, h=(d1000)tan(28)h = (d - 1000) \cdot \tan(28^\circ).

  3. Set the equations for hh equal to each other: dtan(24)=(d1000)tan(28)d \cdot \tan(24^\circ) = (d - 1000) \cdot \tan(28^\circ)

  4. Solve for dd: Expanding and rearranging terms, we get: dtan(24)=dtan(28)1000tan(28)d \cdot \tan(24^\circ) = d \cdot \tan(28^\circ) - 1000 \cdot \tan(28^\circ) d(tan(24)tan(28))=1000tan(28)d \cdot (\tan(24^\circ) - \tan(28^\circ)) = -1000 \cdot \tan(28^\circ) d=1000tan(28)tan(28)tan(24)d = \frac{1000 \cdot \tan(28^\circ)}{\tan(28^\circ) - \tan(24^\circ)}

  5. Substitute the values of the tangents:

    • tan(24)0.4452\tan(24^\circ) \approx 0.4452
    • tan(28)0.5317\tan(28^\circ) \approx 0.5317

    d=10000.53170.53170.4452d = \frac{1000 \cdot 0.5317}{0.5317 - 0.4452} d531.70.08656148.84 feetd \approx \frac{531.7}{0.0865} \approx 6148.84 \text{ feet}

  6. Calculate the height hh using dd: h=dtan(24)h = d \cdot \tan(24^\circ) h6148.840.44522737.08 feeth \approx 6148.84 \cdot 0.4452 \approx 2737.08 \text{ feet}

Answer:

The height of the mountain is approximately 2737.08 feet, rounded to two decimal places.

Would you like further details on any step?


Related Questions:

  1. How would the answer change if the second observation point was only 500 feet closer?
  2. What is the effect of increasing the angle of elevation in these calculations?
  3. Can this method be used for any two arbitrary angles? Why or why not?
  4. How would you set up a similar problem if you only had the angle from one observation point?
  5. Why does the tangent function work well in this problem?

Tip:

Always double-check trigonometric calculations when using small angle differences, as they can significantly impact the result.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Angle of Elevation
Tangent Function

Formulas

tan(θ) = opposite / adjacent
h = d * tan(θ1)
h = (d - distance) * tan(θ2)

Theorems

Trigonometric Ratios in Right Triangles

Suitable Grade Level

Grades 10-12