Proportions in TrianglesWatch for Parallel Lines,

Transversals, andAngle Bisectors

Side Splitter Theorem(related to Midsegment Theorem)

• If a line is parallel to ONE side of a triangle AND intersects the other two sides, then it divides those other TWO sides proportionally.

Corollary to Side Splitter

2nd Example

(In order for the lines to be parallel, then the side portions must be proportional. Right?

Triangle-Angle-Bisector Theorem

• If a line bisects an angle of a triangle, then it divides the opposite side into 2 segments which are proportional to the OTHER TWO sides of the triangle.

A

Examples

HomeworkPractice (Key Attached) Extra Credit2 34 6 , 79 1013 1526 25 2831 3248 49 , 50 and below