High School

The isosceles triangle has a perimeter of 7.5 m. Which equation can be used to find the value of [tex]x[/tex] if the shortest side, [tex]y[/tex], measures 2.1 m?

A. [tex]2x - 2.1 = 7.5[/tex]
B. [tex]4.2 + y = 7.5[/tex]
C. [tex]y - 4.2 = 7.5[/tex]
D. [tex]2.1 + 2x = 7.5[/tex]

Answer :

Sure, let's solve the problem step-by-step.

We are given:
- An isosceles triangle with a perimeter of 7.5 meters.
- The shortest side of the triangle, [tex]\( y \)[/tex], measures 2.1 meters.

In an isosceles triangle, the two longer sides are equal. Let's denote the length of each of these sides by [tex]\( x \)[/tex].

Since we know the perimeter of the triangle is the sum of all its sides, we can write the following equation:
[tex]\[ y + x + x = 7.5 \][/tex]

Given [tex]\( y = 2.1 \)[/tex], we substitute it into the equation:
[tex]\[ 2.1 + x + x = 7.5 \][/tex]

This simplifies to:
[tex]\[ 2.1 + 2x = 7.5 \][/tex]

Looking at the given options:
1. [tex]\( 2x - 2.1 = 7.5 \)[/tex]
2. [tex]\( 4.2 + y = 7.5 \)[/tex]
3. [tex]\( y - 4.2 = 7.5 \)[/tex]
4. [tex]\( 2.1 + 2x = 7.5 \)[/tex]

We see that the correct equation that matches our simplified equation is:
[tex]\[ 2.1 + 2x = 7.5 \][/tex]

Thus, the answer is:
[tex]\[ 2.1 + 2x = 7.5 \][/tex]

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