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Angle Angle Side Postulate

Proving Congruent Triangles with AAS

The Angle Angle Side postulate (often abbreviated as AAS) states that if two angles and the non-included side one triangle are congruent to two angles and the non-included angle of another triangle, then these two triangles are congruent.
Worksheet & Activity on the Angle Angle Side Postulate
 Example of Angle Angle Side Proof (AAS)  


Identify Angle Angle Side relationship



Identify which pair of triangles below does NOT illustrate an angle angle side (AAS) relationship.
Answer

Identify Angle Angle Side relationship (AAS)
Practice Proofs


Prove $$ \triangle ABC \cong \triangle DEC $$

loading AAS proof


Prove $$ \triangle ABC \cong \triangle DEF $$

loading AAS proof


Can you identify the error in the AAS proof below?

What is wrong with the proof below?
Answer
The error involves the side needed to prove two triangles congruent by the Angle Angle Side Postulate . FE and BC are NOT full sides in either triangle. You would need to use the additon property of equality to add segment BE to FE and BE to be able to state that their is a pair of congruent sides in the two triangles.