# Definition:Quadrilateral/Dart

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## Definition

A **dart** is an irregular quadrilateral with a reflex angle.

## Also defined as

Some sources prefer to reserve the term **dart** for a reflex-angled trapezium which has both pairs of adjacent sides equal, for example $EFGH$ in the diagram above.

Other uses restrict the term specifically to the **dart** in the Penrose tiles.

## Also known as

A **dart** whose adjacent sides are equal is also called a **deltoid**.

## Also see

## Sources

- 2008: David Nelson:
*The Penguin Dictionary of Mathematics*(4th ed.) ... (previous) ... (next): Entry:**deltoid**:**1.**