Unit 2 — Geometry Proofs

Segments, angle pairs, transversals, and parallel lines — everything you need for two-column proofs, organized by lesson.

Reasons bank

Given Def. of Midpoint Def. of Vertical Angles Def. of Linear Pair Def. of Complementary/Supplementary Def. of Congruent Angles Segment Addition Post. Linear Pair Post. Vertical Angles Thm. Triangle Sum Thm. Triangle Sum Corollary Exterior Angle Thm. Corresponding ∠s Post. Alt. Interior ∠s Thm. Alt. Exterior ∠s Thm. Consecutive Int. ∠s Thm. Substitution Reflexive Transitive Add./Sub. Prop. of Equality

Before you submit a proof

  • ✓Does every statement have a reason that actually matches it?
  • ✓Did you use the Given info in your first line(s)?
  • ✓Proving a converse theorem? Make sure you didn't cite that same theorem.
  • ✓Named both the transversal and the two lines it crosses?
  • ✓Exterior angle problem? Confirm it forms a linear pair AND sits outside the triangle.