Angles in triangles (age 12+)
Know and use the criteria for triangle congruence (SSS, SAS, ASA, RHS), use standard labelling conventions for sides and angles of triangle ABC, and determine whether two triangles are congruent
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“If your child is shown two triangles where all three sides of one match all three sides of the other, can they explain why those triangles must be identical in shape and size?”
Full guide and materials
- Activity. Know and use the criteria for triangle congruence (SSS, SAS, ASA, RHS), use standard labelling conventions for sides and angles of triangle ABC, and determine whether two triangles are congruent
What to notice. State which congruence criterion (SSS, SAS, ASA, or RHS) applies to a given pair of triangles • Use the notation △ABC ≅ △DEF and match corresponding sides and angles • Determine whether given measurements produce a unique triangle, more than one, or none
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If your child is shown two triangles where all three sides of one match all three sides of the other, can they explain why those triangles must be identical in shape and size?
Know and use the criteria for triangle congruence (SSS, SAS, ASA, RHS), use standard labelling conventions for sides and angles of triangle ABC, and determine whether two triangles are congruent
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Check understanding
- State which congruence criterion (SSS, SAS, ASA, or RHS) applies to a given pair of triangles
- Use the notation △ABC ≅ △DEF and match corresponding sides and angles
- Determine whether given measurements produce a unique triangle, more than one, or none
“If your child is shown two triangles where all three sides of one match all three sides of the other, can they explain why those triangles must be identical in shape and size?”
Curriculum record
- Type
- Conceptual
- Subject
- Mathematics
- Domain
- Geometry
- Age range
- Ages 12–14
Standards