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There are 4 tests that can be used, depending upon what you have:

1) SSS (Side-Side-Side) - all three corresponding sides of the triangles are equal.

2) AAS (Angle-Angle-Side) - two corresponding angles and one corresponding side are equal

3) SAS (Side-Angle-Side) - two corresponding sides and the *ENCLOSED* angle are the same

4) RHS (Right angle-Hypotenuse-Side) - The triangles are Right-angled with Hypotenuse and corresponding side equal

In test 2, if two angles are given then the third angle can be calculated, thus the order does not matter and ASA(Angle-Side-Angle) is equivalent and also proves congruency.

Note the importance in test 3 that the angle is enclosed between the corresponding sides. If it is not enclosed, the triangles may be congruent, but they may also NOT be congruent. In this case the test you are using is Angle-Side-Side (ASS - which is what you would be to say that the triangles are congruent).

Note that RHS is a special case of ASS (the only one which guarantees congruency) in that the angle MUST be a right angle (90°); this means that the third side of both triangles can be calculated using Pythagoras and RHS is effectively SSS.

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Q: How do you know if a two triangles are congruent?
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What postulate or theorem verifies the congruence of triangles?

sssThere are five methods for proving the congruence of triangles. In SSS, you prove that all three sides of two triangles are congruent to each other. In SAS, if two sides of the triangles and the angle between them are congruent, then the triangles are congruent. In ASA, if two angles of the triangles and the side between them are congruent, then the triangles are congruent. In AAS, if two angles and one of the non-included sides of two triangles are congruent, then the triangles are congruent. In HL, which only applies to right triangles, if the hypotenuse and one leg of the two triangles are congruent, then the triangles are congruent.


What are three ways that you can prove that triangles are congruent?

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What does CPCTC mean in math terms?

CPCTC is an acronym for the phrase 'corresponding parts of congruent triangles are congruent' It means that once we know that two triangles are congruent, we know that all corresponding sides and angles are congruent.


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