2D shapes: sides and corners
A polygon is a flat shape with straight sides. It has the same number of corners (vertices) as sides.
| Sides | Name | Sides | Name |
|---|---|---|---|
| 3 | triangle | 6 | hexagon |
| 4 | quadrilateral | 7 | heptagon |
| 5 | pentagon | 8 | octagon |
A regular shape has all sides the same length and all angles the same size.
Quadrilaterals (4 sides)
| Shape | What makes it special |
|---|---|
| Square | 4 equal sides, 4 right angles |
| Rectangle | opposite sides equal, 4 right angles |
| Rhombus | 4 equal sides, but no right angles (a “pushed-over square”) |
| Parallelogram | opposite sides equal and parallel (a “pushed-over rectangle”) |
| Trapezium | exactly one pair of parallel sides |
| Kite | two pairs of equal sides that are next to each other |
Triangles
| Triangle | Sides |
|---|---|
| Equilateral | all 3 sides equal (and all angles 60°) |
| Isosceles | exactly 2 sides equal |
| Scalene | no sides equal |
| Right-angled | one angle is a right angle (90°) |
3D shapes: faces, edges and vertices
- Face: a flat (or curved) surface
- Edge: where two faces meet
- Vertex (plural vertices): a corner, where edges meet
| Shape | Faces | Edges | Vertices |
|---|---|---|---|
| Cube | 6 | 12 | 8 |
| Cuboid | 6 | 12 | 8 |
| Square-based pyramid | 5 | 8 | 5 |
| Triangular prism | 5 | 9 | 6 |
| Cylinder | 3 (2 flat, 1 curved) | 2 | 0 |
Watch out! A square is a special kind of rectangle (and a special rhombus too). The dashed lines on 3D pictures are edges hidden at the back: count them!
Top tip: for a prism, count the shape at the end. A triangular prism has triangle ends: 3 + 3 = 6 vertices.
🗂️ Count the sides1 of 9
How many sides does this shape have? Tap the right box.
Rhombus
🎮 Shape detectiveQuestion 1 of 5