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Question 9 (Multiple Choice Worth 1 point)

[tex]$\Delta EFG$[/tex] is located at [tex]$E(0,0)$[/tex], [tex]$F(-7,4)$[/tex], and [tex]$G(0,8)$[/tex]. Which statement is true?

A. [tex]$\triangle EFG$[/tex] is a scalene triangle.
B. [tex]$\triangle EFG$[/tex] is an isosceles triangle.
C. [tex]$\triangle EFG$[/tex] is an equilateral triangle.
D. [tex]$\triangle EFG$[/tex] is a right triangle.


Sagot :

To determine the type of triangle [tex]\(\Delta EFG\)[/tex] formed by the points [tex]\(E(0,0)\)[/tex], [tex]\(F(-7,4)\)[/tex], and [tex]\(G(0,8)\)[/tex], we need to calculate the lengths of the sides and examine their properties.

1. Calculating the lengths of the sides:
- The length [tex]\(EF\)[/tex] between points [tex]\(E(0,0)\)[/tex] and [tex]\(F(-7,4)\)[/tex]:
[tex]\[ EF = \sqrt{(-7 - 0)^2 + (4 - 0)^2} = \sqrt{49 + 16} = \sqrt{65} \approx 8.062 \][/tex]
- The length [tex]\(FG\)[/tex] between points [tex]\(F(-7,4)\)[/tex] and [tex]\(G(0,8)\)[/tex]:
[tex]\[ FG = \sqrt{(0 - (-7))^2 + (8 - 4)^2} = \sqrt{49 + 16} = \sqrt{65} \approx 8.062 \][/tex]
- The length [tex]\(GE\)[/tex] between points [tex]\(G(0,8)\)[/tex] and [tex]\(E(0,0)\)[/tex]:
[tex]\[ GE = \sqrt{(0 - 0)^2 + (8 - 0)^2} = \sqrt{0 + 64} = \sqrt{64} = 8.0 \][/tex]

2. Determining the properties of the triangle:
- To check if the triangle is scalene (all sides have different lengths):
[tex]\[ \text{EF} \approx 8.062 \neq \text{FG} \approx 8.062 \text{ and } \text{FG} \approx 8.062 \neq \text{GE} = 8.0 \text{ and } \text{GE} = 8.0 \neq \text{EF} \approx 8.062 \][/tex]
Since at least two sides are equal, the triangle is not scalene.

- To check if the triangle is isosceles (at least two sides have the same length):
[tex]\[ \text{EF} \approx 8.062 = \text{FG} \approx 8.062 \][/tex]
Since two of its sides are equal, the triangle is isosceles.

- To check if the triangle is equilateral (all three sides have the same length):
[tex]\[ \text{EF} \approx 8.062 \neq \text{GE} = 8.0 \][/tex]
Since not all three sides are equal, the triangle is not equilateral.

- To check if the triangle is a right triangle (Pythagorean theorem):
[tex]\[ \text{EF}^2 + \text{FG}^2 \approx (8.062)^2 + (8.062)^2 = 65 + 65 = 130 \neq (8.0)^2 = 64 \][/tex]
The side lengths do not satisfy the Pythagorean theorem, so the triangle is not a right triangle.

Since the triangle is not scalene, equilateral, or right, the correct statement is:

- [tex]\(\triangle EFG\)[/tex] is an isosceles triangle.

So, the correct choice is:
[tex]\[ \boxed{\triangle EFG \text{ is an isosceles triangle.}} \][/tex]