The perimeter of a scalene triangle is 14.5 cm. The longest side is twice that of the shortest side. Which equation can be used to find the side lengths if the longest side measures 6.2 cm?

Choose the correct answer.

A. [tex]6.2 + b = 14.5[/tex]
B. [tex]9.3 + b = 14.5[/tex]
C. [tex]12.4 + b = 14.5[/tex]
D. [tex]18.6 + b = 14.5[/tex]



Answer :

Let's break down the problem step by step.

1. Total Perimeter and Longest Side:
- Given perimeter of the triangle is [tex]\( 14.5 \)[/tex] cm.
- The longest side measures [tex]\( 6.2 \)[/tex] cm.

2. Relation between Longest Side and Shortest Side:
- The longest side is twice the shortest side.
- Let's denote the shortest side by [tex]\( a \)[/tex]. Thus, [tex]\( 2a = 6.2 \)[/tex] cm.

3. Calculating the Shortest Side:
[tex]\[ 2a = 6.2 \implies a = \frac{6.2}{2} = 3.1 \text{ cm} \][/tex]

4. Summation of the Sides:
- Since the perimeter is the sum of all the sides, let the middle side be [tex]\( b \)[/tex].
- We can set up the equation for the perimeter:
[tex]\[ a + b + \text{longest side} = 14.5 \][/tex]
- Substituting the known values:
[tex]\[ 3.1 + b + 6.2 = 14.5 \][/tex]

5. Solving for the Middle Side ([tex]\(b\)[/tex]):
[tex]\[ 3.1 + 6.2 + b = 14.5 \implies 9.3 + b = 14.5 \][/tex]
[tex]\[ b = 14.5 - 9.3 = 5.2 \text{ cm} \][/tex]

6. Verification of the Equation:
- The equation is [tex]\( 9.3 + b = 14.5 \)[/tex].

Therefore, the correct equation that can be used to find the side lengths is:
[tex]\[ 9.3 + b = 14.5 \][/tex]

Thus, the correct answer is:
[tex]\[ \boxed{9.3+b=14.5} \][/tex]