Math Problem Statement

  1. In order to determine the height of a California redwood tree, two sightings from the ground, one 200 feet directly behind the other are made. If the angles of inclination were 45 degrees and 30 degrees respectively, how tall is the tree to the nearest foot

Solution

We can solve this problem using trigonometry, specifically the tangent function.

Step 1: Define Variables

Let:

  • hh be the height of the tree.
  • dd be the horizontal distance from the first observation point to the base of the tree.
  • The two observation points be 200 feet apart.

From the problem:

  • The first observer sees the tree at an angle of 4545^\circ.
  • The second observer (200 feet further away) sees the tree at an angle of 3030^\circ.

Step 2: Use the Tangent Function

From the first observation point: tan(45)=hd\tan(45^\circ) = \frac{h}{d} Since tan45=1\tan 45^\circ = 1, we get: h=dh = d

From the second observation point: tan(30)=hd+200\tan(30^\circ) = \frac{h}{d+200} Since tan30=13\tan 30^\circ = \frac{1}{\sqrt{3}}, we get: hd+200=13\frac{h}{d+200} = \frac{1}{\sqrt{3}}

Step 3: Solve for hh

We substitute h=dh = d into the second equation: dd+200=13\frac{d}{d+200} = \frac{1}{\sqrt{3}} Multiply both sides by d+200d+200: d=d+2003d = \frac{d+200}{\sqrt{3}} Multiply by 3\sqrt{3} to eliminate the fraction: d3=d+200d \sqrt{3} = d + 200 Rearrange: d3d=200d \sqrt{3} - d = 200 Factor out dd: d(31)=200d (\sqrt{3} - 1) = 200 Solve for dd: d=20031d = \frac{200}{\sqrt{3} - 1}

Step 4: Rationalize the Denominator

Multiply numerator and denominator by 3+1\sqrt{3} + 1: d=200(3+1)(31)(3+1)d = \frac{200 (\sqrt{3} + 1)}{(\sqrt{3} - 1)(\sqrt{3} + 1)} Since (31)(3+1)=31=2(\sqrt{3} - 1)(\sqrt{3} + 1) = 3 - 1 = 2, we simplify: d=200(3+1)2d = \frac{200 (\sqrt{3} + 1)}{2} d=100(3+1)d = 100 (\sqrt{3} + 1) Approximating 31.732\sqrt{3} \approx 1.732: d100(1.732+1)=100(2.732)=273.2d \approx 100 (1.732 + 1) = 100 (2.732) = 273.2

Since h=dh = d, we get: h273 feeth \approx 273 \text{ feet}

Final Answer:

The height of the tree is 273 feet.

Would you like further explanation or a diagram? Here are some related questions:

  1. How would the answer change if the angles of inclination were different?
  2. Can we solve this problem using a different trigonometric approach?
  3. How does changing the distance between the two observation points affect the calculation?
  4. What happens if the ground is not level between the observers and the tree?
  5. How does this problem relate to real-world surveying techniques?

Tip: Always check the reasonableness of your answer by considering the real-world scale of the object being measured!

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Angles of Elevation
Right Triangle Trigonometry

Formulas

tan(θ) = opposite / adjacent
h = d
d = 200 / (sqrt(3) - 1)
h = 100 (sqrt(3) + 1)

Theorems

Tangent Function
Triangle Proportionality Theorem

Suitable Grade Level

Grades 9-12