What is a rectangle?
A rectangle is a flat shape with four straight sides and four right angles, where the opposite sides are equal.
The answer
A rectangle has 4 sides, 4 vertices and 2 pairs of parallel sides. The one drawn here has 2 lines of symmetry. A square, the special rectangle with equal sides, has 4. The angles inside a rectangle add up to 360°.
Rectangle diagram and properties
| Property | Count |
|---|---|
| Sides | 4 |
| Vertices (corners) | 4 |
| Angles add up to | 360° |
| Right angles | 4 |
| Pairs of parallel sides | 2 |
| Lines of symmetryA square, the special rectangle with equal sides, has 4. | 2 |
Key facts about the rectangle
- Opposite sides are equal and parallel, so a rectangle is a special parallelogram.
- Its 2 lines of symmetry go across the middle each way. The diagonals are not lines of symmetry.
- Area = length × width, and perimeter = 2 × (length + width).
- The two diagonals are the same length and cut each other in half.
Where you see it
A door, a book cover, a phone screen and a football pitch.
The common mistake
Thinking the diagonals of a rectangle are lines of symmetry. Fold a paper rectangle along a diagonal and the corners do not meet, so it has only 2 lines of symmetry.
An 11+ style question
A rectangle has a perimeter of 30 cm and is 9 cm long. How wide is it?
Answer: 6 cm
- Half the perimeter is one length and one width: 30 ÷ 2 = 15 cm.
- 15 − 9 = 6, so the rectangle is 6 cm wide.
- Check: 9 + 6 + 9 + 6 = 30.
Related shapes and skills
More shapes
Questions parents ask
How many sides and vertices does a rectangle have?
A rectangle has 4 straight sides and 4 vertices (corners). Its angles add up to 360°.
How many lines of symmetry does a rectangle have?
A rectangle that is not a square has 2: one down the middle and one across the middle. A square has 4, because its diagonals are lines of symmetry too.
Is a rectangle a parallelogram?
Yes. Its opposite sides are parallel and equal, which makes it a parallelogram with four right angles.
Shape questions are quick marks in the 11+
Angles, symmetry, nets and 3D shapes come up in 11+ maths and non-verbal reasoning. The free diagnostic checks maths, English and both kinds of reasoning, and shows what to practise next. No card is required.