College

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.

1. Understanding the Problem:
- We are given that we have an isosceles triangle.
- The perimeter of this triangle is 7.5 meters.
- The shortest side [tex]\( y \)[/tex] measures 2.1 meters.
- We need to find an equation to solve for [tex]\( x \)[/tex], which represents the lengths of the other two equal sides of the triangle.

2. Setting Up the Equation:
- For an isosceles triangle, two sides are of equal length, and the third side is different (here it's given as the shortest side [tex]\( y \)[/tex]).
- Let's denote the lengths of the equal sides as [tex]\( x \)[/tex].

3. Formulating the Perimeter Equation:
- The perimeter of the triangle is the sum of all its sides.
- The formula for the perimeter of our isosceles triangle here will be:
[tex]\[
x + x + y = 7.5
\][/tex]
Simplifying this, we get:
[tex]\[
2x + y = 7.5
\][/tex]

4. Substituting the Known Value:
- We are given that [tex]\( y = 2.1 \)[/tex].
- Substitute [tex]\( y \)[/tex] in the equation:
[tex]\[
2x + 2.1 = 7.5
\][/tex]

So, the equation we can use to find the value of [tex]\( x \)[/tex] is:
[tex]\[
2.1 + 2x = 7.5
\][/tex]

Thus, the correct option from the provided choices is:
[tex]\[
2.1 + 2x = 7.5
\][/tex]