- Basic Proportionality Theorem Or Thales Theorem
- (Prove) If a Line is Drawn Parallel to One Side of a Triangle to Intersect the Other Two Sides in Distinct Points, the Other Two Sides Are Divided in the Same Ratio.
- Converse of Basic Proportionality Theorem Or Thales Theorem - (Motivate) If a Line Divides Two Sides of a Triangle in the Same Ratio, the Line is Parallel to the Third Side