2D shapes: Types and properties

In a nutshell

2D shapes are flat shapes that are sometimes called plane shapes. There are many different types of 2D shapes. Regular polygons have equal side lengths and equal angles.

Polygons

Polygons are straight-sided shapes. Regular polygons have sides of equal length, and equal angles. Irregular polygons have at least one side or angle that is different in size. Below are examples of polygons. 

Examples

• A triangle has three sides.
  

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• A quadrilateral is a shape that has four sides.

• A pentagon has five sides.

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• A hexagon has six sides.

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• A heptagon has seven sides.

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• An octagon has eight sides.
  

Quadrilaterals

Quadrilaterals are four-sided shapes. There are a number of different types of quadrilateral:

Square

• Four sides of equal length.
• Four right angles.
• The diagonals meet at right angles.
• Two pairs of parallel sides.
  

Rectangle

• Two pairs of equal sides.
• Four right angles.
• Two pairs of parallel sides.
  

Rhombus

• Four sides of equal length.
• Opposite sides are parallel.
• Opposite angles are equal.
  

Parallelogram

• Opposite sides are the same length.
• Opposite sides are parallel.
• Opposite angles are equal.
  

Trapezium

• One pair of parallel sides.
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Kite

• Two pairs of equal sides next to each other.
• No sides are parallel.
  

Triangles

A triangle is a 2D plane shape with three straight sides and three angles. There are four types of triangle:

Equilateral triangle

• All three sides are equal.
• All three angles are equal.
  

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Isosceles triangle

• Two sides are equal.
• Two angles are equal.
  

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Scalene triangle

• All sides are different.
• All angles are different.
  

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Right angled triangle

• One angle is a right angle.
  
  
  

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Circles

A circle is a shape made up of all points in a plane that are a fixed distance from the centre. There are a number of properties of a circle:

• Radius - the distance from the edge to the centre of a circle.
• Diameter - the distance across a circle through its centre.
• Circumference - the length of the outside edge of a circle.

Note: The diameter of a circle is twice the radius.