SAS means side, angle, side, and refers to the fact that two sides and the included angle of a triangle are known. The SAS Similarity Theorem states that if two sides in one triangle are proportional to two sides in another triangle and the included angle in both are congruent, then the two triangles are similar.Click to see full answer. Also know, is SAS a theorem or postulate? SAS Postulate Yes! There’s the Side-Angle -Side postulate, or SAS. This states that if two sides and the included angle of one triangle are congruent to two sides and the included angle of another triangle, then the triangles are congruent.Also Know, is Asa a similarity postulate? Congruent Triangles – Two angles and included side (ASA) Definition: Triangles are congruent if any two angles and their included side are equal in both triangles. There are five ways to test that two triangles are congruent. This is one of them (ASA). Considering this, how are the SAS Similarity Theorem and the SAS congruence postulate alike How are they different? How are they different? Both use two pairs of corresponding sides and the included angles by those sides, but SAS ~ uses pairs of equal ratios, while SAS Congruence uses pairs of congruent sides.How do you prove in SAS?You can prove that triangles are similar using the SAS~ (Side-Angle-Side) method. SAS~ states that if two sides of one triangle are proportional to two sides of another triangle and the included angles are congruent, then the triangles are congruent.