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MATHEMATICSGeometry
CURRENT TOPIC2D Shapes
● Not StartedFoundation 20 minTopic 1 of 8

2D Shapes

Names, properties, symmetry, and classification of flat shapes — the foundation of all geometry in 11+ papers.

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What you'll learn

4 core skill areas across this topic

🔷
Name & Classify
Identify all types of triangles, quadrilaterals, and polygons by their properties
📐
Angles & Lines
Spot parallel lines, perpendicular lines, and calculate interior angles
🪞
Line Symmetry
Count lines of symmetry and draw them accurately for any 2D shape
🔄
Rotational Symmetry
Find the order of rotational symmetry for triangles, quadrilaterals & polygons
△

Triangles

4 types — classified by sides or angles

Equilateral
3 equal sides & angles (60° each)
Isosceles
2 equal sides & 2 equal angles
Scalene
All sides & angles different
Right-Angled
One angle exactly 90°
∑

Angles in any triangle always add up to 180° — no exceptions.

□

Quadrilaterals

6 types — all have 4 sides totalling 360°

Square
4 equal sides, 4 right angles
Rectangle
4 right angles, opposite sides equal
Rhombus
4 equal sides, opposite angles equal
Parallelogram
2 pairs of parallel sides
Trapezium
Exactly 1 pair of parallel sides
Kite
2 pairs of adjacent equal sides

Remember: A square is a special rectangle AND a special rhombus — it belongs to both families!

⬡

Regular Polygons & Circles

Equal sides, equal angles — and one very special case

Pentagon
5 sides · interior angles sum = 540°
Hexagon
6 sides · interior angles sum = 720°
Octagon
8 sides · interior angles sum = 1080°
Circle
Infinite sides · infinite lines of symmetry

Interior angle sum of any polygon = (n − 2) × 180°, where n is the number of sides.

🪞

Symmetry

Two types tested at 11+

|
Line Symmetry
Square — 4 lines
Equilateral triangle — 3 lines
Rectangle (not square) — 2 lines
Regular pentagon — 5 lines
Circle — infinite lines
↻
Rotational Symmetry
Equilateral triangle — order 3
Order = how many times it fits in 360°
Equilateral triangle — order 3
Square — order 4
Regular hexagon — order 6

Key facts to remember

∑

Angles in any triangle always sum to 180°

⬛

A square is a special rectangle AND a special rhombus

♾️

A circle has infinitely many lines of symmetry

🔢

Exterior angles of any polygon always sum to 360°

Ready to practise?

Choose your mode — or dive straight in

Warm-Up
Pass mark
60%
Questions
8–10
Core
Pass mark
65%
Questions
10–12
Pro
Pass mark
70%
Questions
12–15
Start Learning — 2D Shapes