Math Problem Statement

For a project in her Geometry class, Violet uses a mirror on the ground to measure the height of her school's football goalpost. She walks a distance of 6.65 meters from the goalpost, then places a mirror flat on the ground, marked with an X at the center. She then walks 4.25 more meters past the mirror, so that when she turns around and looks down at the mirror, she can see the top of the goalpost clearly marked in the X. Her partner measures the distance from her eyes to the ground to be 1.75 meters. How tall is the goalpost? Round your answer to the nearest hundredth of a meter.

Solution

This problem is based on the concept of similar triangles, which can be used to calculate the height of the football goalpost.

Step 1: Understanding the geometry

Violet and the top of the goalpost are forming two similar triangles with the mirror as the point where the light rays reflect. Here’s what we know:

  1. The distance from the goalpost to the mirror is 6.65 meters.
  2. The distance from Violet to the mirror is 4.25 meters.
  3. Violet's eye height from the ground is 1.75 meters.
  4. We need to find the height of the goalpost, which we will call hh.

Since the triangles are similar, the ratio of corresponding sides is equal: h6.65=1.754.25\frac{h}{6.65} = \frac{1.75}{4.25}

Step 2: Set up the equation

Using the proportional relationship of similar triangles, we can set up the equation as follows: h6.65=1.754.25\frac{h}{6.65} = \frac{1.75}{4.25}

Step 3: Solve for hh

Multiply both sides of the equation by 6.65 to isolate hh: h=1.754.25×6.65h = \frac{1.75}{4.25} \times 6.65

Now, let’s calculate the value of hh.The height of the goalpost is approximately 2.74 meters, rounded to the nearest hundredth.

Would you like more details, or have any questions on the process?

Here are 5 related questions you could explore:

  1. How are similar triangles used in real-life measurements like this?
  2. What is the importance of mirror reflections in geometric problems?
  3. How would the calculation change if the distances were different?
  4. How can we verify the accuracy of the height measurement using another method?
  5. Could this technique work if Violet were at a different height?

Tip: Always ensure the angles in similar triangle problems are consistent to apply proportional reasoning correctly.

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Math Problem Analysis

Mathematical Concepts

Geometry
Similar Triangles
Proportions

Formulas

h / 6.65 = 1.75 / 4.25

Theorems

Theorem of Similar Triangles

Suitable Grade Level

Grades 9-11