1. BASIC PROPORTIONALITY THEOREM IF A LINE IS DRAWN II TO ONE SIDE OF A TRI. TO INTERSECT THE OTHER TWO SIDES IN DISTINCT POINTS, THEN THE OTHER TWO SIDES ARE DIVIDED IN THE SAME RATIO.

2. CONVERSE OF BASIC PROPORTIONALITY THEOREM IF A LINE DIVIDES ANY TWO SIDES OF A TRI. IN THE SAME RATIO, THEN THE LINE IS II TO THE THIRD SIDE.

3. SIMILARITY CRITERIA AAA SIMILARITY CRITERION AA SIMILARITY CRITERION SSS SIMILARITY CRITERION SAS SIMILARITY CRITERION

4. AREA THEOREM THE RATIO OF THE AREAS OF TWO SIMILAR TRIANGLES ARE EQUAL TO THE RATIO OF THE SQUARES OF ANY TWO CRRESPONDING SIDES