A quarter circle is one quarter of a circle, namely a circular arc with central
angle 
radians (
). For radius 
, its arc length is
 |
The region bounded by a quarter circle and two perpendicular radii is a quarter-disk.
The pattern above is constructed from tangents to quarter-circles, repeated using reflections and translations (Trott 2004, pp. 18-19). The circular arcs themselves are not drawn. The envelopes consist of four quarter-circles and resemble astroids, but an astroid is not composed of four quarter-circles.
