MathematicsGeometryAges 11–14
Angle sums in triangles and polygons
Derive and use the angle sum in a triangle (180°), use it to deduce the angle sum in any polygon ((n−2) × 180°), and calculate interior and exterior angles of regular polygons
Learning resources
Reviewed external links that reinforce this concept. They do not replace Gakuva’s teaching approach.
No reviewed resources for this concept yet.
The teaching approach above still stands. Curated practice links will appear here as the shelf fills.
Explore the learning path
3 before · 1 after
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Before
This concept
Angle sums in triangles and polygonsProcedural concept
Check understanding
- Calculate a missing angle in a triangle by subtracting the known angles from 180°
- Find the sum of interior angles in a hexagon by dividing it into triangles
- Calculate each interior and exterior angle of a regular polygon given the number of sides
“If your child knows two angles of a triangle are 50° and 70°, can they work out the third? And can they figure out the angles inside a regular pentagon?”
Curriculum record
- Type
- Procedural
- Subject
- Mathematics
- Domain
- Geometry
- Age range
- Ages 11–14
Standards
ccss-math:8.G.5uk-nc-2013:KS3.Maths.Geo.12