we are asked to determine the perimeter of quadrilateral ADEF. The perimeter is the sum of the sides of a figure, therefore, the perimeter "P" is:
![P=AD+DE+EF+FA](https://img.qammunity.org/2023/formulas/mathematics/high-school/gnp8wfk4uarcg37s34pxtvp3gzqbjscsb3.png)
Now, we have that DE = FA and AD = EF, therefore:
![P=2AD+2DE](https://img.qammunity.org/2023/formulas/mathematics/high-school/vbb9xz6gtwicz41uok89spkq1to5ocxtrz.png)
Since triangle DEF is midsegments of triangle ABC we have 2AD = AB and 2DE = AC, therefore:
![P=AB+AC](https://img.qammunity.org/2023/formulas/mathematics/high-school/r26skv5bilbnblwkcf55m0hp4hzac74xf4.png)