🔷 2D Shapes

Triangles, quadrilaterals, polygons and symmetry!

📖 Learn
Shape properties
✏️ Examples
Worked problems
🔬 Visualiser
Interactive tools
🎯 Practice
20 mixed questions

📖 2D Shapes

1. Triangles

TypeEqual SidesEqual Angles
Equilateral3 equal sides3 × 60°
Isosceles2 equal sides2 equal base angles
ScaleneNo equal sidesNo equal angles
Right-angledVariesOne angle = 90°

2. Quadrilaterals

ShapeProperties
Square4 equal sides, 4 right angles
RectangleOpposite sides equal, 4 right angles
Rhombus4 equal sides, opposite angles equal
ParallelogramOpposite sides parallel and equal
TrapeziumOne pair of parallel sides

3. Regular Polygons

A regular polygon has all sides equal AND all angles equal.

Pentagon = 5 sides   Hexagon = 6   Octagon = 8

A regular polygon with n sides has n lines of symmetry.

4. Lines of Symmetry

A line of symmetry folds a shape in half so both sides match exactly.

ShapeLines of Symmetry
Square4
Rectangle2
Equilateral triangle3
Isosceles triangle1
Parallelogram0

5. Properties Summary

Key facts to remember:

✏️ Worked Examples

Example 1 – Equal sides of a triangle

How many equal sides does an isosceles triangle have?

Isosceles triangle → 2 equal sides
Answer: 2

Example 2 – Lines of symmetry

How many lines of symmetry does a square have?

Square: 4 vertical/horizontal + 2 diagonal = 4 total
Answer: 4

Example 3 – Number of sides

How many sides does a pentagon have?

"Penta" means five
Answer: 5

Example 4 – Regular polygon symmetry

How many lines of symmetry does a regular hexagon have?

A regular polygon with n sides has n lines of symmetry
Hexagon has 6 sides → 6 lines of symmetry

Example 5 – Vertices

How many vertices does an octagon have?

"Octa" means eight → 8 sides
Number of vertices = number of sides = 8

🔬 Shape Visualiser

Draw a Regular Polygon


Triangle Identifier






Symmetry Lines


Exercise 1 – Equal Sides in Triangles

Enter the number of equal sides each triangle has.

Exercise 2 – Lines of Symmetry (Quadrilaterals)

Enter the number of lines of symmetry.

Exercise 3 – Number of Sides

Enter the number of sides each polygon has.

Exercise 4 – Lines of Symmetry (Regular Polygons)

Enter the number of lines of symmetry.

Exercise 5 – Number of Vertices

Enter the number of vertices each shape has.

🎯 Practice – 20 Questions

🏆 Challenge