Use the distance formula: distance = sqrt[ (x2 - x1)2 + (y2 - y1)2 ]
to find these distances: AB, BC, BA, DE, EF, FA
For example: BC: B = (x1, y1) = (2, 0) C = (x2, y2) = (3, 4)
BC = sqrt[ (3 - 2)2 + (4 - 0)2 ] = sqrt[ (1)2 + (4)2 ] = sqrt[ 1 + 16 ] = sqrt(17)
If these triangles are congruent, the corresponding sides will have equal lengths
and
if the corresponding sides have equal lengths, the triangles will be congruent.