Circle

WMA link


Circle[{$c_x$, $c_y$}, r]

draws a circle with center ($c_x$, $c_y$) and radius r.

Circle[{$c_x$, $c_y$}, {$r_x$, $r_y$}]

draws an ellipse.

Circle[{$c_x$, $c_y$}]

chooses radius 1.

Circle[]

chooses center (0, 0) and radius 1.

Target practice:

Arrowheads
Directive