The following two-column proof with missing statements and reasons proves that if a line parallel to one side of a triangle also
intersects the other two sides, the line divides the sides proportionally: Statement Reason
1. Line segment DE is parallel to line segment AC 1. Given
2. Line segment AB is a transversal that intersects two parallel lines. 2. Conclusion from Statement 1.
3. ∠BDE ≅ ∠BAC 3. Corresponding Angles Postulate
4. 4.
5. 5.
6. BD over BA equals BE over BC 6. Converse of the Side-Side-Side Similarity Theorem
Parallel lines have the same slope. in your current equation you have a slope of <u>-1</u>. We can use this slope and your set of points in the point slope formula.
