From the triangle shown, we have three important informations:
- It is a right triangle, because it has a right angle, mHEF.
- Its hypotenuse has length 8, HF = 8.
- Its two legs has the same length, HE = EF.
Because it is a right triangle, we can use the Pythagora's Theorem:

And we know that:

Thus:
![\begin{gathered} EF^2+EF^2=8^2 \\ 2EF^2=64 \\ EF^2=32 \\ EF=\sqrt[]{32} \\ EF=\sqrt[]{2^5} \\ EF=4\sqrt[]{2} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/9ji7fc54eqdrtfby9klxjqd6nggb6vcajd.png)