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Triangle Congruence

Triangle Congruence, a selection of answers from the Dr. Math archives.

Triangle Congruence

I don't understand how to tell if two triangles are congruent.

Congruence and Triangles

Can you please explain how to determine, using SSS, SAS, and ASA, how a shape is congruent or not?

SSS, ASA, SAS Proofs

I understand the ideas, but I'm not sure when and where to use them.

SSA Theorem: Valid or Invalid?

Why can't the SSA Theorem be used to prove congruence?

SSA Proof

Proving congruence using the Side-Side-Angle Theorem.

SSA and Non-congruent Triangles

Why can't you conclude that two triangles are congruent when side-side-angle are congruent?

Angle-Side-Side Does Not Work

Can you give me a construction to show that Angle-Side-Side does not prove two triangles congruent?

Congruent Triangles - SSS Test

How do you know if two triangles are congruent?

Congruent and Similar Triangle Theorems

Is there an Angle-Angle-Angle (AAA) triangle congruency theorem?

Determining Triangle Similarity

Given two triangles, how can you determine if they are similar?

Congruent Parts Congruent Triangles Congruent (CPCTC)

When should we use CPCTC, and how does it prove anything?

Theorem or Postulate?

Shouldn't the three triangle postulates - SSS, ASA, and SAS - be theorems?