Summary
S. N.Â  FigureÂ  NameÂ  Area in sq. units  PerimeterÂ  Nomenclature 
1.  CircleÂ  Ï€r^{2}Â  2Ï€rÂ 
r = radius 

2.  SectorÂ of theÂ circle 
Â (or) lr 
l + 2rÂ
Â 
Î¸ = angle of theÂ sectorÂ r = radius, l = length of theÂ sector arc 

3.  SemicircleÂ  Â½ Ï€r^{2}Â  Ï€r + 2r  r = radius  
4.  SegmentÂ of a circleÂ (shaded)Â  r = radius, Â Î¸ = angle of theÂ sector 

5.  RingÂ (shadedÂ portion)Â 
Ï€(R^{2 } r^{2})  2Ï€(R  r)  R=outer radius Â r=Inner radius 