Step-by-step explanation:
Part A.
To get from D to E, we go 5 units right and 2 units up, then we can write the following equation to find the length DE
![5^2+2^2=DE^2](https://img.qammunity.org/2023/formulas/mathematics/college/fo56x9bxat1ka8ajts80ne6f0ym8pphnnm.png)
Solving for DE, we get
![\begin{gathered} DE^2=5^2+2^2 \\ DE^2=25+4 \\ DE^2=29 \\ DE=√(29) \\ DE=5.4 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/wpwfpgcegwzf34anhji0l954mh3ljx45lp.png)
Therefore, DE = 5.4 units
Part B.
To get from D to F, we go 5 units right and 4 units down, so we can write the following equation to find the length of DF
![5^2+4^2=DF^2](https://img.qammunity.org/2023/formulas/mathematics/college/ed68qoft7eh7hrwcto1nzc69v14e9zwcgj.png)
Solving for DF, we get
![\begin{gathered} DF^2=5^2+4^2 \\ DF^2=25+16 \\ DF^2=41 \\ DF=√(41) \\ DF=6.4 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/xzmtm1agy2mjeppma0g0vrcjrujpf1sxyk.png)
Therefore, the length of DF is 6.4 units
Part C.
Then, the perimeter is the sum of all the sides of the triangle, so
Perimeter = DE + DF + FE
Perimeter = 5.4 + 6.4 + 6
Perimeter = 17.8 units