🔢 Mathematics · Geometry
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
Typical age: 11–14 years
“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?”
0 / 3 mastered
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Needs first
- Angles in triangles (age 10+)REQUIRED
Extends KS2 angle sums in triangles and quadrilaterals to general polygons
- Algebraic Notation
Expressing angle sum as (n-2)×180 requires algebraic notation for the general formula
- Understanding angles (age 11+)REQUIRED
Polygon angle sums require fluency with basic angle properties