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 :

Let's denote the two equal sides by [tex]$x$[/tex] and the base (shortest side) by [tex]$y$[/tex]. The perimeter [tex]$P$[/tex] of the isosceles triangle is given by

[tex]$$
2x + y = 7.5.
$$[/tex]

Since we are told that the shortest side measures [tex]$2.1\text{ m}$[/tex], we substitute [tex]$y=2.1$[/tex] into the equation:

[tex]$$
2x + 2.1 = 7.5.
$$[/tex]

This is the equation that can be used to find the value of [tex]$x$[/tex]. Next, if we want to find [tex]$x$[/tex], we subtract [tex]$2.1$[/tex] from both sides:

[tex]$$
2x = 7.5 - 2.1 = 5.4.
$$[/tex]

Then, by dividing both sides by [tex]$2$[/tex], we find:

[tex]$$
x = \frac{5.4}{2} = 2.7.
$$[/tex]

So, the equation corresponding to the triangle's dimensions is

[tex]$$
2.1 + 2x = 7.5.
$$[/tex]

Thus, the correct option is the fourth one.