G.TR.2.a

Use definitions, postulates, and theorems (including Side-Side-Side (SSS); Side-Angle-Side (SAS); Angle-Side-Angle (ASA); Angle-Angle-Side (AAS); and Hypotenuse-Leg (HL)) to prove and justify two triangles are congruent.

Example Problems
A sequence of transformations is described below.
1. A reflection over a line
2. A dilation about the point P
What must be preserved under this sequence of transformations: angle measures and/or segment lengths?
A sequence of transformations is described below.
1. A translation
2. A rotation about a point A
3. A reflection over a line
What must be preserved under this sequence of transformations: angle measures and/or segment lengths?
A sequence of transformations is described below.
1. A rotation about a point S
2. A dilation about the same point S
What must be preserved under this sequence of transformations: angle measures and/or segment lengths?
Khan Academy Resources
Triangle congruence reviewDetermine congruent trianglesJustify triangle congruenceProve triangle propertiesProve triangle congruenceTriangle congruence postulates/criteriaDetermining congruent trianglesProving the SAS triangle congruence criterion using transformationsProving the SSS triangle congruence criterion using transformationsCalculating angle measures to verify congruenceProving the ASA and AAS triangle congruence criteria using transformationsProving triangle congruence
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