What you’ll learn
Select appropriate congruence criterion.
Key idea
An included angle is where the given sides meet; an included side joins the two given angle vertices.
Criterion depends on explicit equality positions; shape does not fix size and error cases cannot import extra givens.
Worked example
Classify examples and non-examples for the concept 'Select appropriate congruence criterion'.
Two triangles with A-D, B-E, C-F correspondence have AB=DE=18, BC=EF=24, AC=DF=30. Classify the directly encoded congruence criterion with its evidence.
- The given pattern is SSS: three corresponding side pairs match.
- Use only the explicitly supplied independent equalities; a criterion name alone is not evidence.
Answer: SSS — three corresponding side pairs match.
Quick Check
Classify examples and non-examples for the concept 'Select appropriate congruence criterion'.
Two triangles with A-D, B-E, C-F correspondence have AB=DE=12, AC=DF=16, included A=D=60 degrees. Classify the directly encoded congruence criterion with its evidence.