Question

The isosceles triangle has a perimeter of 7.5m.Which equation can be used to find the value of x if the shortest side,y, measures 2.1m?a) 2x – 2.1 = 7.5b) 4.2 + y = 7.5c) y – 4.2 =7.5d) 2.1 + 2x = 7.5

Answer 1

Solution:

An Isosceles triangle has two out of three of its sides to be equal.

Thus, we have

Given that the perimeter of the triangle is 7.5 m, this implies that

$x+x+y=7.5$

The shortest side of the triangle is y.

This implies that

$y=2.1\text{ m}$

By substitution, we have

$\begin{gathered} x+x+2.1=7.5 \\ \Rightarrow2x+2.1=7.5 \end{gathered}$

Hence, the equation that can be used to find the value of x is

$2x+2.1=7.5$

The correct option is D