Two triangles are similar if they have:
all their angles equalcorresponding sides are in the same ratioBut we don't need to know all three sides and all three angles ...two or three out of the six is usually enough.
There are three ways to find if two triangles are similar: AA, SAS and SSS:
9m - 14n
9m - 13
9m2 + 13n2
-5mn