Well, Aml says they're congruent. I don't think they CAN be ... There's no way you can slide one around and make it fit exactly on top of the other one. They appear to be mirror-images of each other ... maybe.
But AML says they're congruent. So let's assume that the longest sides of both triangles have the same length. Then the length of FE in the standing-up triangle is the same as the distance between points 'A' and 'C' in the lying-down triangle.
Point A . . . . . (0, 1) Point C . . . . . (3, 2) .
The distance between them is
square root of (square of difference in 'x' + square of difference in 'y').
Difference in 'x' . . . . . 3 Difference in 'y' . . . . . 1