
Geometry August 09 Proof
Posted:
Jun 10, 2010 12:24 PM


Greetings!
While reviewing question 38 on the Geometry August 2009 exam, a student of mine mentioned a unique way to prove AB parallel to CD. His reasoning:
1. BF and DE are both perpendicular to AC and thus are parallel.
2. As angles 1 and 2 are given congruent, AB is parallel to CD.
We justified statement 1, and reasoned that 2 congruent angles containing a pair of parallel rays must also have its other rays parallel.
Has anyone else seen such reasoning? Can the justification be cleaned up a bit?

