The triangles I'm using are in the image as well as the question. I'm not sure if I'm doing it right


SOLUTION
Given the question in the question tab, the following are the solution steps to answer the question.
STEP 1: Write the given length of triangle ABC
[tex]\begin{gathered} AB=5,BC=5,AC=? \\ U\sin g\text{ pythagoras theorem,} \\ AC^2=5^2+5^2 \\ AC^2=25+25=50 \\ AC=\sqrt[]{50}=\sqrt[]{2\times25}=\sqrt[]{2}\times\sqrt[]{25}=5\sqrt[]{2} \end{gathered}[/tex]STEP 2: We carry out the second part of the direction in the question.
[tex]\begin{gathered} AB=5,DE\text{ is the corresponding side with length of 2} \\ \frac{DE}{AB}=\frac{2}{5}=0.4 \\ ratio\text{ = 0}.4 \end{gathered}[/tex]STEP 3: Use the ratio to multiply the other sides
[tex]\begin{gathered} U\sin g\text{ the sides listed in Step , we multiply the other two sides of triangle ABC with the ratio.} \\ BC=5,EF=0.4\times5=2 \\ \\ AC=5\sqrt[]{2},DF=0.4\times5\sqrt[]{2}=2\sqrt[]{2} \end{gathered}[/tex]