The SAS Triangle Congruence Theorem states that if 2 sides and their included angle of one triangle are congruent to 2 sides and their included angle of another triangle, then those triangles are congruent. The applet below uses transformational geometry to prove this  theorem. Play with this applet below for a few minutes, then answer the questions that follow.  You can  move the BIG WHITE POINTS anywhere you'd like on the screen to see what happens 
Questions: 1) What geometry transformations did you observe in the applet above? List them. 2) What common trait do all these transformations (you listed in your response to (1)) have? 3) Go to this link and complete the first 5 exercises in this GeoGebra Book chapter.