I am asked to prove the SAS (side-angle-side) and ASA(angle-side-angle) congruence of triangles in absolute geometry ( the geometry based in the axiom system of Euclides with the parallel postulate removed).
How do I even prove two triangles are congruent without using the SAS, ASA or SSS criteria? Do I have to see the congruence between any of sides or angles of the two triangles?