Math Problem Statement

To measure the distance EF across a lake, a surveyor at S locates points E, F, G, and H as shown. What is the length of EF?

Solution

To find the length of EFEF, we can use the fact that triangles GHS\triangle GHS and FES\triangle FES are similar, as noted in the hint. This similarity implies that the ratios of corresponding sides are equal. Here’s the step-by-step approach:

  1. Identify Corresponding Sides in Similar Triangles:

    • Since GHSFES\triangle GHS \sim \triangle FES, we know: GHFE=HSES=GSFS\frac{GH}{FE} = \frac{HS}{ES} = \frac{GS}{FS}
  2. Set Up the Proportion:

    • From the diagram:
      • GH=20GH = 20 m
      • HS=26HS = 26 m
      • ES=32.5ES = 32.5 m
    • We want to find FEFE, so we’ll use the ratio: GHFE=HSES\frac{GH}{FE} = \frac{HS}{ES}
  3. Plug in the Known Values and Solve for FEFE: 20FE=2632.5\frac{20}{FE} = \frac{26}{32.5} Cross-multiply to solve for FEFE: 20×32.5=FE×2620 \times 32.5 = FE \times 26 650=26×FE650 = 26 \times FE FE=65026FE = \frac{650}{26} FE=25 mFE = 25 \text{ m}

So, the length of EFEF is 25 meters.

Would you like further explanation on any part of this process?


Here are 5 related questions for further practice:

  1. What is the definition of similar triangles, and why are corresponding side ratios equal?
  2. How can you determine if two triangles are similar based on their angles and sides?
  3. What is the relationship between the scale factor and corresponding side lengths in similar triangles?
  4. If GHGH was measured to be different, say 22 m, how would you solve for EFEF with the new value?
  5. Can similar triangles be used in three-dimensional space, and if so, how?

Tip: When working with similar triangles, always ensure that you correctly match corresponding sides to maintain the proportion.

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Math Problem Analysis

Mathematical Concepts

Similar Triangles
Proportions

Formulas

\( \frac{GH}{FE} = \frac{HS}{ES} \)

Theorems

Triangle Similarity Theorem

Suitable Grade Level

Grades 8-10