If both legs are the same length, this is called an isosceles trapezoid, and both base angles are the same.
If the legs are parallel, it now has two pairs of parallel sides, and is a parallelogram.
In coordinate geometry, if you know the coordinates of the four vertices,
you can calculate various properties of it, including the altitude and median.
For more on this, see Trapezoid definition (Coordinate Geometry)
There is considerable confusion over the definition of 'trapezoid' and 'trapezium' due to differences in the British and US versions.
As you can see from the table below, the meanings of the two words are exactly reversed between the US and British interpretations.