Mathematics·Geometry·conceptual
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
Suggested ages 12–14
Evidence of 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
Assessment prompt
If Angles in triangles (age 12+) 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?
Standards alignment
8.G.2US · ccss-math
Congruence via rigid motions
Common Core State Standards for Mathematics · 8
KS3.Maths.Geo.6GB · uk-nc-2013
Labelling Conventions and Triangle Congruence
The national curriculum in England: Key stages 1 and 2 framework document · Key Stage 3