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Given and Prove

Part of the Congruence & Proof section of Coddy's Geometry journey. Lesson 1 of 60.

$Two right angles marked with squares, one drawn with short arms and one with long arms$

Both corners have the small square, so both are right angles. One is drawn much bigger. A ruler cannot show for sure that they are equal. A proof can. A proof is a list of statements. Each statement has a reason. A reason is a given fact, like a mark, or a rule, like all right angles are equal.

Challenge

Two right angles are marked with squares. The three statements are already written. Give each statement its reason. If a reason uses earlier lines, pick those lines. Then press Check.

Try it yourself

$Write the proof$

Write the proof

All lessons in Congruence & Proof

1What a Proof Is

Given and ProveChaining Equal Parts Your First Full Proof Recap: A Chain of Reasons

4SAS

The Included Angle The SAS Rule SAS with a Shared Side Why SSA Fails SAS or SSS?Recap: SAS

7Using CPCTC

Congruent, Then Equal Proving a Bisector Flowchart Proofs Proving a Midpoint Recap: Using CPCTC

10Isosceles Triangle Proofs

Base Angles in a Proof Equal Angles, Equal Sides Proving Isosceles The Perpendicular Bisector Chasing in Isosceles Shapes Recap: Isosceles Proofs

2Congruent Triangles

Same Size, Same Shape What Congruence Gives Recap: Matching Parts

5ASA and AAS

The Side Between The ASA Rule The AAS Rule ASA or AAS?Recap: ASA and AAS

8Proofs with Vertical Angles

Vertical Angles in Proofs The Bowtie Bowtie with ASA Linear Pairs in Proofs Recap: Vertical Angles

11Similarity Proofs

AA Similarity Two Right Triangles SSS Similarity SAS Similarity Similar, Then Find Recap: Similarity