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]xy - 4.2 = 7.5[/tex]
D. [tex]2.1 + 2x = 7.5[/tex]

Answer :

To find the value of [tex]\( x \)[/tex] for the given isosceles triangle, let's break it down:

1. Understand the Problem:
- You have an isosceles triangle, which means it has two sides of the same length.
- The perimeter of the triangle is given as 7.5 meters.
- The shortest side, [tex]\( y \)[/tex], measures 2.1 meters.

2. Set Up the Equation:
- In an isosceles triangle, let the two equal sides be [tex]\( x \)[/tex] each.
- The perimeter of the triangle is the sum of all its sides: [tex]\( 2x + y \)[/tex].
- Therefore, the equation for the perimeter is:
[tex]\[
2x + 2.1 = 7.5
\][/tex]

3. Solve the Equation for [tex]\( x \)[/tex]:
- Subtract 2.1 from both sides to isolate the term with [tex]\( x \)[/tex]:
[tex]\[
2x = 7.5 - 2.1
\][/tex]
[tex]\[
2x = 5.4
\][/tex]

- Divide both sides by 2 to solve for [tex]\( x \)[/tex]:
[tex]\[
x = \frac{5.4}{2}
\][/tex]
[tex]\[
x = 2.7
\][/tex]

Based on the given choices, the correct equation that helps find the value of [tex]\( x \)[/tex] is:
[tex]\[
2.1 + 2x = 7.5
\][/tex]

This equation correctly represents the relationship between the sides of the triangle and its perimeter. Using this, we've verified that each of the equal sides (x) measures 2.7 meters.