How does a rectangular trapezoid look?

A rectangular trapezoid (also called right-angled trapezoid, right trapezoid) has such kind:

Rectangular trapezoid

A rectangular trapezoid always has two right angles. On a picture direct corners are marked little squares in tops A and D. Direct corners can be situated in two any contiguous tops of trapezoid.

Rectangular trapezoid

On this picture of rectangular trapezoid direct corners are located in tops B and С.

In mathematics there is determination of rectangular trapezoid, which over is brought and in Wikipedia: the rectangular is name a trapezoid at which even one corner of line. This classic determination of rectangular trapezoid, bluntly rewritten from sacred mathematical books. In Euclidean geometry a rectangular trapezoid always has two lines of corner, as two sides trapezoids, called grounds, are parallel. Segment BC, formative a direct corner with founding of АВ, will be always perpendicular to the second founding of CD. With one or three direct corners there can be only a curvilinear rectangular trapezoid, and it is quite another other class of geometrical figures already.

For blondes helped to draw kria, author of blog kria-tiv.