Math Problem Statement

A boat is heading towards a lighthouse, whose beacon-light is 127 feet above the water. From point AA, the boat’s crew measures the angle of elevation to the beacon, 12degrees∘, before they draw closer. They measure the angle of elevation a second time from point BB at some later time to be 24degrees∘. Find the distance from point AA to point BB. Round your answer to the nearest tenth of a foot if necessary.

Solution

To solve for the distance between points AA and BB, we will use trigonometry, specifically the tangent function for the angles of elevation from points AA and BB.

Let:

  • h=127h = 127 feet (the height of the lighthouse beacon above the water)
  • θA=12\theta_A = 12^\circ (angle of elevation at point AA)
  • θB=24\theta_B = 24^\circ (angle of elevation at point BB)
  • dAd_A = distance from point AA to the base of the lighthouse
  • dBd_B = distance from point BB to the base of the lighthouse
  • dABd_{AB} = distance between points AA and BB (the distance we need to find)

Step 1: Calculate the distance dAd_A

Using the tangent function at point AA: tan(12)=hdA\tan(12^\circ) = \frac{h}{d_A} Solving for dAd_A: dA=htan(12)d_A = \frac{h}{\tan(12^\circ)} Using a calculator: tan(12)0.2126\tan(12^\circ) \approx 0.2126 dA=1270.2126597.4 feetd_A = \frac{127}{0.2126} \approx 597.4 \text{ feet}

Step 2: Calculate the distance dBd_B

Using the tangent function at point BB: tan(24)=hdB\tan(24^\circ) = \frac{h}{d_B} Solving for dBd_B: dB=127tan(24)d_B = \frac{127}{\tan(24^\circ)} Using a calculator: tan(24)0.4452\tan(24^\circ) \approx 0.4452 dB=1270.4452285.3 feetd_B = \frac{127}{0.4452} \approx 285.3 \text{ feet}

Step 3: Calculate the distance dABd_{AB}

The distance between points AA and BB is the difference between dAd_A and dBd_B: dAB=dAdBd_{AB} = d_A - d_B dAB=597.4285.3312.1 feetd_{AB} = 597.4 - 285.3 \approx 312.1 \text{ feet}

Thus, the distance from point AA to point BB is approximately 312.1 feet.

Would you like more details or have any questions?

Here are 8 related questions:

  1. How do you find the height of an object using the tangent function?
  2. What is the tangent function and how is it used in angle elevation problems?
  3. How do you determine distances using angles of elevation and trigonometry?
  4. What happens to the angles of elevation as you get closer to the lighthouse?
  5. Can you explain the significance of using two different angles of elevation?
  6. How can this method be applied to find the distance between two points in other scenarios?
  7. What are the limitations of using trigonometry for these types of problems?
  8. How can you ensure the accuracy of your trigonometric calculations?

Tip: Always double-check the unit mode on your calculator (degrees or radians) when performing trigonometric calculations to ensure accurate results.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Angle of Elevation

Formulas

Tangent function

Theorems

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Suitable Grade Level

Grades 10-12