Area and perimeter of a rectangle
- A rectangle is a quadrangle all inner angles of which are right.
- The opposite edges are parallel and equally long.
- The diagonals are the same length; they halve one another but are not perpendicular to one another.
rectangle
| a, b | edge |
| d | diagonal |
| α, β | angles formed by diagonals |
| C | circumcircle |
| R | radius (circumcircle) |
| O | center |
