1.7Introduction to Geometric Proof
Quick Answer
A geometric proof starts with Given information and ends with the Prove statement. Each step uses a definition, postulate, theorem, or property as its reason. Common reasons: Segment Addition Postulate, Angle Addition Postulate, Definition of Midpoint, Definition of Angle Bisector.
Essential Question
How do we structure a two-column geometric proof, and what types of reasons are acceptable?
Learning Goals
- 1Identify the Given and Prove in a proof problem.
- 2Write two-column proofs about segments and angles.
- 3Use definitions, postulates, and properties as reasons.
- 4Apply the Reflexive, Symmetric, and Transitive Properties of Congruence.
Key Vocabulary
Given
The information provided at the start of a proof.
Prove
The statement to be established at the end of a proof.
Reflexive Property of Congruence
Any segment or angle is congruent to itself.
Symmetric Property of Congruence
If AB ≅ CD, then CD ≅ AB.
Transitive Property of Congruence
If AB ≅ CD and CD ≅ EF, then AB ≅ EF.
Full lesson content coming soon
Worked examples, guided practice problems, a workbook, quiz, and downloadable PDF resources will be added to this lesson in Phase 2. The learning goals and vocabulary above reflect the complete lesson scope.