Definition:Quadrilateral/Dart

From ProofWiki
Jump to navigation Jump to search

Definition

A dart is an irregular quadrilateral with a reflex angle.

Darts.png


Deltoid

A deltoid is a dart such that:

the $2$ sides which are adjacent to the reflex angle are equal to each other
the other $2$ sides are also equal to each other.


Also defined as

Some sources prefer to reserve the term dart for what we define on $\mathsf{Pr} \infty \mathsf{fWiki}$ as a deltoid, that is, 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 Penrose dart in the Penrose tiles.


Also see