# Week 6 Day 1 Lesson Summary

Our focus for today was about precision and making convincing arguments for why ideas are true.
Make a convincing argument for why *ABCD* is congruent to *A'B'C'D'*.

Make a convincing argument for why angle *B* is congruent to angle *B'*.

We have a new word in your glossary today. Open up the glossary page titled "Unit 1 Symmetry and Angle Relationships" and read through the new entry.

- Vertical Angle Theorem