How can you tell they’ve got it: Angles in triangles (age 12+)?

If they’ve got it, you’ll see things like: 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. Or just try it together: 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?

Mathematics Geometry Ages 12–14

Angles in triangles (age 12+)

Your child can tell when two triangles are exactly the same shape and size. If all three sides match, the triangles must be identical.

In curriculum terms

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

Ages are typical, not deadlines — follow your child’s pace. How to help at home →

How to tell they’ve got it

Tick these off as you see them — no test required.

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

🖨 Print this page to keep the checklist — it prints beautifully.

Try this together

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?

Where this sits on the map

Stuck here? Check the skills it builds on first. Confident? Here’s what it unlocks.

Builds on

Measuring anglesages 11–13Determining congruence requires constructing triangles from given conditions

Types of anglesages 11–13Triangle congruence criteria require standard labelling conventions

Angles in triangles (age 12+)this skill · ages 12–14

Unlocks

Nothing on the map depends on this yet.

solid = must come firstdashed = helps

Curriculum alignment

Where this fits in the official school curriculum — our best automated guess, not yet checked by a person.

This skill sits beyond Year 6 in the Australian Curriculum, so no F–6 code is matched. It also sits beyond the NSW K–6 syllabuses. It also sits beyond Level 6 in the Victorian Curriculum.

Nearby on the map

Angles with parallel linesages 12–14 Circles: Circumference & Areaages 12–14 Coordinatesages 12–14 Understanding anglesages 12–14

All Geometry skills →