Perimeter is the sum of all sides of a shape
then if we sum all sides of the triangle we have 26
we write this like a equation making the missing measure x
![7+7+x+x=26](https://img.qammunity.org/2023/formulas/mathematics/college/6nq6hka0nv8g6jtgvhzibtelia4fawfxw4.png)
simplify
![14+2x=26](https://img.qammunity.org/2023/formulas/mathematics/college/5eezkz6xxai0g7hipere08tlj0kzyput4l.png)
and find x subtracting 14 on both sides
![\begin{gathered} 14-14+2x=26-14 \\ 2x=12 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/z0jv6yf3kkt0yuri280fvzpsu3my8fj3pl.png)
and dividing by 2 to solve x
![\begin{gathered} (2x)/(2)=(12)/(2) \\ \\ x=6 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/74ggavhj534umih3aqtea5zi82vewc7uqv.png)
the value of the missing side is 6
we can check finding the perimeter again
![\begin{gathered} 7+7+6+6 \\ 14+12 \\ =26 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/yezj6e0g0o6cndalt840lv9w865bfigfo3.png)
perimeter is right then the values of the side is right too