Part i)
The perimeter is the sum of the measures of all the sides of a geometric figure.
Then, we can write the following equation:
![\begin{gathered} \text{ Perimeter }=AB+BC+AC \\ \text{ We replace the known values} \\ 17=AB+x+8 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/6yd3ztfj6mg6dwk7nu3k9dxl3gh5l4qd0b.png)
Now, we can solve the above equation for AB:
![\begin{gathered} \text{ Subtract x and subtract 8 from both sides of the equation} \\ 17-x-8=AB+x+8-x-8 \\ 17-x-8=AB \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/1qyqk6upja3iaz1b6x9ay6xbym0wxyq3r2.png)
Therefore, the expression, in terms of x, for the length of AB is:
![AB=17-x-8](https://img.qammunity.org/2023/formulas/mathematics/college/ypq7ylyv6rbmn6e9bw051beipkwmlxrk6g.png)
Part ii)
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