The following properties arise from the definition:
- Two of the pairs of adjacent angles sum to 180o
- The area is the mean of the parallel sides multiplied by the distance between them.
- The perimeter is equal to the sum of the oblique sides plus the sum of the tangent sides.
- The sum of the oblique angles will be equal to the sum of the tangent angles.
- "Trapezium". Britannica Online Dictionary.