Write proof that proves triangle ABD is congruent to BAC, More info below.

The big shape is a rectangle. The rectangle is split in opposite corners. The corners take shape into two separate triangles because of the line. If you would split like a square or like that, a rectangle, it would end up being equivalent. That is because the rectangle is not lopsided. If the rectangle was lopsided, then the triangles would not be equal.

1/6 of a chance i would believe