Rhombus
A Quadrilateral with both pairs of opposite sides Parallel and all sides the same length, i.e., an equilateralParallelogram. The word Rhomb is sometimes used instead of rhombus, and a rhombus is sometimes also called adiamond. The Diagonals 
and 
of a rhombus are perpendicular and satisfy
The Area of a rhombus is given by
A rhombus whose Acute Angles are 45° is called a Lozenge.See also Diamond, Lozenge, Parallelogram, Quadrilateral, Rhombic Dodecahedron,Rhombic Icosahedron, Rhombic Triacontahedron, Rhomboid, Skew Quadrilateral, Trapezium, Trapezoid
References
Beyer, W. H. (Ed.) CRC Standard Mathematical Tables, 28th ed. Boca Raton, FL: CRC Press, p. 123, 1987.
- Peg Solitaire
- Peg Top
- Peirce's Theorem
- p-Element
- Pell Equation
- Pell-Lucas Number
- Pell-Lucas Polynomial
- Pell Number
- Pell Polynomial
- Pell Sequence
- Pencil
- Penrose Stairway
- Penrose Tiles
- Penrose Triangle
- Penrose Tribar
- Pentabolo
- Pentacle
- Pentacontagon
- Pentad
- Pentadecagon
- Pentaflake
- Pentagon
- Pentagonal Antiprism
- Pentagonal Cupola
- Pentagonal Deltahedron