Math Problem Statement

The shadow of a vertical tower on a level ground increases by 10m, when the altitude of the Sun changes from 45° to 30°. Find the height of the tower correct to two decimal places.

Solution

The question involves a trigonometric problem that can be solved using tangent relationships and involves a tower's height and its shadow.

Problem:

  • Given:

    1. The altitude of the sun changes from 4545^\circ to 3030^\circ.
    2. The shadow increases by 10m10 \, \text{m}.
  • To Find: The height hh of the tower, correct to two decimal places.


Solution:

  1. At 4545^\circ:

    • Using the tangent formula: tan(45)=height of the tower (h)length of the shadow at 45(x).\tan(45^\circ) = \frac{\text{height of the tower (h)}}{\text{length of the shadow at } 45^\circ (x)}. Since tan(45)=1\tan(45^\circ) = 1, we have: h=x.h = x.
  2. At 3030^\circ:

    • Similarly, using the tangent formula: tan(30)=height of the tower (h)length of the shadow at 30(x+10).\tan(30^\circ) = \frac{\text{height of the tower (h)}}{\text{length of the shadow at } 30^\circ (x + 10)}. Since tan(30)=13\tan(30^\circ) = \frac{1}{\sqrt{3}}, we have: 13=hx+10.\frac{1}{\sqrt{3}} = \frac{h}{x + 10}.
  3. Substituting h=xh = x from the first equation into the second: 13=xx+10.\frac{1}{\sqrt{3}} = \frac{x}{x + 10}.

  4. Cross-multiplying and simplifying: x+10=3x.x + 10 = \sqrt{3} \cdot x. x(31)=10.x(\sqrt{3} - 1) = 10. x=1031.x = \frac{10}{\sqrt{3} - 1}.

  5. Rationalizing the denominator: x=10(3+1)(31)(3+1).x = \frac{10(\sqrt{3} + 1)}{(\sqrt{3} - 1)(\sqrt{3} + 1)}. x=10(3+1)2.x = \frac{10(\sqrt{3} + 1)}{2}. x=5(3+1).x = 5(\sqrt{3} + 1).

  6. Calculating xx: Using 31.732\sqrt{3} \approx 1.732: x=5(1.732+1)=52.732=13.66m.x = 5(1.732 + 1) = 5 \cdot 2.732 = 13.66 \, \text{m}.

  7. Finding hh: Since h=xh = x, the height of the tower is: h=13.66m.h = 13.66 \, \text{m}.


Final Answer:

The height of the tower is 13.66 meters.


Do you want further explanation or a breakdown of any step?

Related Questions:

  1. What is the significance of rationalizing the denominator in such problems?
  2. How do tangent functions relate to real-world problems like this?
  3. Can you derive the formula for the shadow length as a function of the height and sun's angle?
  4. What other angles apart from 3030^\circ and 4545^\circ could simplify the math?
  5. How does changing the angle to 6060^\circ instead affect the problem's solution?

Tip:

Always double-check tangent values and trigonometric simplifications in problems involving angles to avoid errors.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Tangent Function
Geometry

Formulas

tan(angle) = height / shadow length
tan(45°) = 1
tan(30°) = 1 / √3

Theorems

Properties of Tangent Function
Trigonometric Ratios

Suitable Grade Level

Grades 10-12