What you’ll learn
Choose similarity criterion.
Key idea
Match the given evidence to angle pairs, all three side ratios, or two side ratios and their included angle.
Choose a criterion from supplied evidence; an opposite angle is not the included angle.
Worked example
Classify examples and non-examples for the concept 'Choose similarity criterion'.
Triangles ABC/DEF have A=D=48 and B=E=52 degrees, with no side data. Select the criterion directly established by these data.
- Two pairs A-D=48, B-E=52 are stated.
- Third angles both 80; AA is justified without claiming equal sizes.
Answer: AA — two corresponding angle pairs are known.
Quick Check
Classify examples and non-examples for the concept 'Choose similarity criterion'.
Triangles ABC/DEF have A=D=33 and B=E=42 degrees, with no side data. Select the criterion directly established by these data.