Half a Circle. The Perimeter of the semicircle of Radius is
and the Area is
The weighted mean of is
The Centroid is then given by
The semicircle is the Cross-Section of a Hemisphere for any Plane through the z-Axis.
See also Arbelos, Arc, Circle, Disk, Hemisphere, Lens, Right Angle,
Salinon, Thales' Theorem, Yin-Yang
© 1996-9 Eric W. Weisstein