rhombus Rhombus 2001-12-12 00:36:09 2007-06-05 05:13:31 Definition rhombi rhombuses \usepackage{amssymb} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{graphicx} \usepackage{xypic} A \emph{rhombus} (plural \emph{rhombi}, or \emph{rhombuses}) is a quadrilateral with its four sides equal. A square is a rhombus, but a rhombus need not be a square, since the angles need not all be equal. Every rhombus is, however, a parallelogram. \begin{center} \includegraphics[scale=2]{rhombus} \end{center} In any rhombus, the diagonals are always perpendicular. A nice result following from this, is that joining the midpoints of the sides, always gives a rectangle. If $D$ and $d$ are the lengths of the diagonals, then the area of the rhombus is \[ \frac{Dd}{2}. \]