# What is a trapezoid? Geometry made simple

You can find an explanation of what a trapezoid is in the area of geometry. You have certainly come across the term “trapezium” here before, without perhaps being able to directly imagine something concrete behind it. However, the properties of a trapezoid can be easily summarised.

## What a trapezoid actually is

Every geometric solid has special properties that it must fulfil in order to be identified as such.

• A trapezoid is generally a quadrilateral that has two parallel sides. These are also called basic sides.
• A trapezoid has four corners and four sides, also called a, b, c and d.
• The four corner angles of the trapezoid add up to 360°. These are also called α, β, γ and δ.
• The length of the legs of a trapezoid is not fixed. They can also be of different lengths.
• There are different forms of the trapezoid. A distinction is made between an isosceles trapezium and a right-angled trapezium.

## Calculations around the trapezoid

If you want to do certain calculations around the trapezoid, it is important to know the appropriate formulae.

• Calculate the area like this: A= ½ × (a+c) × h
• Calculate the perimeter like this: U= a + b + c + d