Math Problem Statement

Correction exercice math en francais merci

Observer la figure puis calculer les longueurs HG et EF

Solution

To solve this exercise, let's calculate the lengths HGHG and EFEF in the given right triangle using the Pythagorean theorem and properties of similar triangles.

Observations from the Figure

  1. We have a right triangle EFG\triangle EFG with a right angle at HH.
  2. EH=2EH = 2 (horizontal segment).
  3. HF=8HF = 8 (vertical segment).
  4. FG=10FG = 10 (hypotenuse of HFG\triangle HFG).

Step 1: Calculating HGHG

Since HFG\triangle HFG is a right triangle with HF=8HF = 8 and HG=xHG = x as the unknown, and FG=10FG = 10 as the hypotenuse, we can apply the Pythagorean theorem:

HG2+HF2=FG2HG^2 + HF^2 = FG^2

Substitute the known values:

HG2+82=102HG^2 + 8^2 = 10^2

HG2+64=100HG^2 + 64 = 100

HG2=10064HG^2 = 100 - 64

HG2=36HG^2 = 36

HG=36=6HG = \sqrt{36} = 6

So, HG=6HG = 6.

Step 2: Calculating EFEF

The segment EFEF can be found using the similarity of triangles EFG\triangle EFG and HFG\triangle HFG. Since HFG\triangle HFG is a smaller, similar triangle with EFEF as the corresponding side of FGFG, we can set up a proportion.

Since EH=2EH = 2, HG=6HG = 6, and FG=10FG = 10, the triangle proportions give:

EFFG=EHHG\frac{EF}{FG} = \frac{EH}{HG}

Substitute the known values:

EF10=26\frac{EF}{10} = \frac{2}{6}

Solve for EFEF:

EF=10×26EF = 10 \times \frac{2}{6}

EF=10×13=1033.33EF = 10 \times \frac{1}{3} = \frac{10}{3} \approx 3.33

So, EF3.33EF \approx 3.33 (or exactly 103\frac{10}{3}).

Final Answer

  • HG=6HG = 6
  • EF=103EF = \frac{10}{3} (approximately 3.333.33)

Would you like further details on any part of the solution?


Here are 5 related questions for further practice:

  1. How would you find the length of EFEF if only FGFG and the angle EFG\angle EFG were given?
  2. Can you find the area of EFG\triangle EFG?
  3. What is the perimeter of EFG\triangle EFG?
  4. How would the calculations change if EFG\triangle EFG were not a right triangle?
  5. Can you verify the similarity between EFG\triangle EFG and HFG\triangle HFG using angle-angle similarity?

Tip: In right triangles, the Pythagorean theorem is a powerful tool to find missing side lengths when you know two sides.

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Math Problem Analysis

Mathematical Concepts

Geometry
Right Triangles
Similar Triangles
Proportions

Formulas

Pythagorean theorem: a^2 + b^2 = c^2
Proportion of similar triangles

Theorems

Pythagorean theorem
Similarity of triangles

Suitable Grade Level

Grades 8-10