What are congruent triangles?
Two triangles are CONGRUENT if they are the same SIZE and SHAPE (although they may be reflections, rotations of each other).
How do we prove that two triangles are congruent?
Happily we don’t have to show that all three sides and all three angles are the same in each triangle.
We only need to show that three of the six things are the same…
…as long as they are the right three!
To do this we MUST use one of the five standard tests: