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
Share and support
Entire curriculum
1590 concepts · 8 subjects
Compare teaching approaches
Teaching approaches
Gakuva’s recommended starting approach is selected. You can still compare every option.
1 approach
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
Family records and proof options
Keep a record of your learning
Save photos, notes, and attendance. Export a proof packet for compliance or portfolio reviews.
Learning resources
External links for extra practice. They do not replace Gakuva’s teaching approach.
No additional resources are listed for this topic.
The teaching approach appears above.
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