Shapes are congruent if you can turn one into the other by moving, rotating or flipping. We can use this symbol [tex]\cong[/tex] to show that two things are congruent. Two triangles are congruent if and only if all the corresponding legs are congruent. The only point that makes the corresponding legs to be congruent is [tex](-1,4)[/tex]. Why? because we can match these two triangles by flipping the red one two times and moving it into the blue one.
