5. You know angles LOY and ROY are congruent, and side OY is incident to both triangles LOY and ROY, which is of course congruent to itself. Triangles LOY and ROY will be congruent if sides OL and OR are also congruent.
6. Similar situation as in (5). MD is incident to both triangles MAD and DEM and is congruent to itself. Angles AMD and EDM are congruent. To use the AAS postulate, you need to know that angles MAD (or just A) and DEM (or just E) are congruent.
