How to write and read the similarity of two triangles ? - Presentation of two similar triangles Theorem 6.3 : If in two triangles, corresponding angles are equal, then their corresponding sides are in the same ratio (or proportion) and hence the two triangles are similar - AAA similarity criterion If two angles of one triangle are respectively equal to two angles of another triangle, then the two triangles are similar - AA similarity criterion for two triangles Theorem 6.4 : If in two triangles, sides of one triangle are proportional to (i.e., in the same ratio of ) the sides of the other triangle, then their corresponding angles are equal and hence the two triangles are similiar - SSS similarity criterion for two triangles Theorem 6.5 : If one angle of a triangle is equal to one angle of the other triangle and the sides including these angles are proportional, then the two triangles are similar - SAS similarity criterion for two triangles.