### Edexcel GCSE Maths

Numbers
Algebra
Geometry and Measures
Probability
Statistics

# 2D Shapes

Two-dimensional (2D) shapes are flat figures that have length and width

There are several common 2D shapes, including polygons and circles. Polygons are closed 2D shapes with n straight sides. Some examples of polygons include:

• Triangles (3 sides)
• Pentagons (5 sides)
• Hexagons (6 sides)
• Octagons (8 sides)

Polygons can be regular (all sides and angles equal), or irregular (varying side lengths and angles). Squares are regular quadrilaterals.

## Triangles

Triangles have three sides and three angles and can be classified as:

• Equilateral – all sides equal and all angles equal to 60°
• Isosceles – two sides equal and base angles equal
• Scalene – no sides equal
• Right-angled – one angle equal to 90°
• Obtuse – one angle greater than 90°
• Acute – all angles less than 90°

Quadrilaterals have four sides and four angles. Some examples include:

• Squares (all sides equal and all angles equal to 90°), so it is a regular quadrilateral
• Rectangles (opposite sides equal, all angles equal to 90°)
• Parallelograms (opposite sides parallel and equal, opposite angles equal)
• Rhombuses (all sides equal, opposite angles equal)
• Trapezoids (one pair of opposite sides parallel)
• Kites (two pairs of adjacent sides equal)

## Circles

Circles are round 2D shapes with no corners or edges, just one curved line that is at a fixed distance from a central point.

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