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 :

To find the equation that can be used to determine the value of [tex]\( x \)[/tex] in an isosceles triangle with a perimeter of 7.5 meters and the shortest side [tex]\( y \)[/tex] measuring 2.1 meters, follow these steps:

1. Understand the properties of the isosceles triangle:
- In an isosceles triangle, two sides are of equal length. Let's denote each of these equal sides by [tex]\( x \)[/tex].
- The third side is given as [tex]\( y \)[/tex] and measures 2.1 meters.

2. Write the equation for the perimeter:
- The perimeter of a triangle is the sum of the lengths of all its sides.
- Therefore, the perimeter of this isosceles triangle can be written as:
[tex]\[
\text{Perimeter} = x + x + y
\][/tex]
- Simplify this to:
[tex]\[
\text{Perimeter} = 2x + y
\][/tex]

3. Substitute the given values:
- The given perimeter is 7.5 meters.
- The shortest side [tex]\( y \)[/tex] is 2.1 meters.
- Substitute these values into the equation:
[tex]\[
7.5 = 2x + 2.1
\][/tex]

4. Rearrange to form the equation:
- Bring the terms involving [tex]\( x \)[/tex] to one side:
[tex]\[
2x + 2.1 = 7.5
\][/tex]

Therefore, the equation that can be used to find the value of [tex]\( x \)[/tex] given the shortest side of the isosceles triangle and the total perimeter is:
[tex]\[
2.1 + 2x = 7.5
\][/tex]

This matches with the fourth option provided:
[tex]\[
2.1 + 2 x = 7.5
\][/tex]