Math Problem Statement

For a project in her Geometry class, Fawzia uses a mirror on the ground to measure the height of her school building. She walks a distance of 11.35 meters from the building, then places a mirror flat on the ground, marked with an X at the center. She then walks 2.05 more meters past the mirror, so that when she turns around and looks down at the mirror, she can see the top of the school clearly marked in the X. Her partner measures the distance from her eyes to the ground to be 1.25 meters. How tall is the school? Round your answer to the nearest hundredth of a meter.

Solution

To solve the problem, we use the principles of similar triangles. Here is a step-by-step breakdown of the solution:

Step 1: Understand the setup

  • hh: The height of the school building (to be determined).
  • d1=11.35md_1 = 11.35 \, \text{m}: Distance from the school to the mirror.
  • d2=2.05md_2 = 2.05 \, \text{m}: Distance from the mirror to Fawzia.
  • hFawzia=1.25mh_{\text{Fawzia}} = 1.25 \, \text{m}: Height of Fawzia's eyes from the ground.

The mirror creates similar triangles:

  1. The large triangle formed by the school building, the mirror, and the top of the building.
  2. The smaller triangle formed by Fawzia, the mirror, and the line of sight to her eyes.

Step 2: Set up the similarity ratio

The heights and corresponding distances of the triangles are proportional: hd1=hFawziad2.\frac{h}{d_1} = \frac{h_{\text{Fawzia}}}{d_2}.

Step 3: Solve for hh

Rearranging the formula: h=hFawziad2d1.h = \frac{h_{\text{Fawzia}}}{d_2} \cdot d_1.

Substitute the known values: h=1.252.0511.35.h = \frac{1.25}{2.05} \cdot 11.35.

First, calculate the fraction: 1.252.050.6098.\frac{1.25}{2.05} \approx 0.6098.

Then, multiply by 11.3511.35: h0.609811.356.92m.h \approx 0.6098 \cdot 11.35 \approx 6.92 \, \text{m}.

Final Answer:

The height of the school building is approximately 6.92 meters.


Would you like further details on any step?
Here are 5 related questions to deepen understanding:

  1. What assumptions are made in this problem regarding the reflection in the mirror?
  2. How would the result change if the mirror were not flat on the ground?
  3. What are other methods to measure the height of tall objects indirectly?
  4. How can trigonometry be applied to solve similar problems?
  5. Why is it important that the top of the school is directly visible in the mirror?

Tip: When solving problems involving similar triangles, carefully label the corresponding sides and angles to avoid confusion.

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Math Problem Analysis

Mathematical Concepts

Similar Triangles
Proportional Reasoning
Geometry

Formulas

h / d1 = h_Fawzia / d2
h = (h_Fawzia / d2) * d1

Theorems

Similarity of Triangles Theorem

Suitable Grade Level

Grades 8-10