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Side-Angle-Side (SAS) Congruence Theorem
See It in Action
Two examples of the idea done right—and one common look-alike that is not right.
EXAMPLE
EXAMPLE
NON-EXAMPLE
Definition
If two sides and the included angle of one triangle are congruent to two sides and the included angle of another triangle, then the two triangles are congruent.
Key points:
The angle must be the included angle, meaning it is directly between the two given sides.
This guarantees that the triangles are fixed in size and shape—so they must be congruent.
SAS is one of the five valid triangle congruence theorems (SSS, SAS, ASA, AAS, HL).
Video
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