2. Similarity Tests for Triangles

3. Angle Angle Similarity Postulate ( AA~) X Y Z RT S Therefore,  XYZ ~  RST by AA~

4. Side-Side-Side Similarity Theorem ( SSS~) X W V RQ P Therefore,  WXV ~  PRQ by SSS~ 3 16 10.5 12 14 4 Put the three sides from the other triangle in order on bottom. Put the three sides from one triangle in order on top. Divide out each ratio and see if all three are the same. If so, the triangles are similar.

5. Side-Angle-Side Similarity Theorem ( SAS~) X W V RQ P Therefore,  WXV ~  PRQ by SAS~ 3 16 12 4 Put the two sides from the other triangle forming the angle in order on bottom. Divide out each ratio and see if both are the same. If so, the triangles are similar. First, make sure you have a pair of corresponding angles congruent. Put the two sides from one triangle that form that angle in order on top.

6. E xamples What parts do you know? Test for SSS~. 61518 10 2530.6 = = Yes!  KML ~  QSR by SSS~

7. E xamples 46 6 9.6rep = Yes!  DCE ~  ACB by SAS~ 1 st, write given info on the figure. AC + CD = AD 6 + CD = 10 CD = 4 4 BC + CE = BE 9 + CE = 15 CE = 6 6 Now, What do you know? You know vertical angles are congruent, so mark them. Next, you know the two sides that form the angles….check for SAS!