For other uses of the word rhombus, see Rhombus (disambiguation)

Two rhombi.

In geometry, a rhombus (or homb; plural rhombi) is a quadrilateral in which all of the sides are of equal length, i.e., it is awith two pairs of equal adjacent sides. The opposite sides of a kite are not parallel unless the kite is also a rhombus. The diagonals of a rhombus are perpendicular to each other. since the norms of AB and BC are equal and since the inner product is bilinear and symmetric. The inner product of the diagonals is zero if and only if they are perpendicular.

Area

The area of any rhombus is a half the product of the lengths of its diagonals:

Because the rhombus is a parallelogram with four equal sides, the area also equals the length of a side (B) multiplied by the perpendicular distance between two opposite sides(H):
A = B×H

Origin

The origin of the word rhombus is from the Greek word for something that spins. Euclid uses the word ρομβος; and in his translation Heath says it is apparently drawn from the Greek word ρεμβω, to turn round and round. He also points out that Archimedes used the term "solid rhombus" for two right circular cones sharing a common base. For more on the origin of the word, see rhombus at the MathWords web page.

External links

• Parallelogram and Rhombus - Animated course (Construction, Circumference, Area)
• Rhombus definition. Math Open Reference With interactive applet.
• Rhombus area. Math Open Reference Shows three different ways to compute the area of a rhombus, with interactive applet.

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