Disk (mathematics)

Common card · No. 394228

In geometry, a disk (also spelled disc) is the region in a plane bounded by a circle. A disk is said to be closed if it contains the circle that constitutes its boundary, and open if it does not. For a radius r {\displaystyle r} , an open disk is usually denoted as D r {\displaystyle D_{r}} , and a closed disk is D r ¯ {\displaystyle {\overline {D_{r}}}} . However in the field of topology the closed disk is usually denoted as D 2 {\displaystyle D^{2}} , while the open disk is int ⁡ D 2...

Read on Wikipedia · Image Jokes Free4Me, Public domain