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The following diagrams show centroids of various two-dimensional objects. A centroid of an object in -dimensional space is the intersection of all hyperplanes that divide into two parts of equal moment about the hyperplane. Informally, it is the "average" of all points of . For an object of uniform composition (mass, density, etc.) the centroid of a body is also its centre of mass. In the case of two-dimensional objects shown below, the hyperplanes are simply lines. | align="center"| | align="center"| |- |Quarter-circular area | align="center"| | align="center"| | align="center"| | align="center"| |- |Semicircular area | align="center" | File:Semicircle centroid2.svg | align="center"| | align="center"| | align="center"| |- |Quarter-elliptical area | align="center" | | align="center"| | align="center"| | align="center"| |- |Semielliptical area | align="center"| | align="center"| | align="center"| | align="center"| |- |Semiparabolic area |The area between the curve and the axis, from to | align="center"| | align="center"| | align="center"| |- |Parabolic area |The area between the curve and the line | align="center"| | align="center"| | align="center"| |- |Parabolic spandrel |The area between the curve and the axis, from to | align="center"| | align="center"| | align="center"| |- |General spandrel |The area between the curve and the axis, from to | align="center"| | align="center"| | align="center"| |- |Circular sector |The area between the curve (in polar coordinates) and the pole, from to | align="center"| | align="center"| | align="center"| |- |Circular segment | align="center"| | align="center"| | align="center"| | align="center"| |- |Quarter-circular arc |The points on the circle and in the first quadrant | align="center"| | align="center"| | align="center"| |- |Semicircular arc |The points on the circle and above the axis | align="center"| | align="center"| | align="center"| |- |Arc of circle |The points on the curve (in polar coordinates) , from to | align="center"| | align="center"| | align="center"| |} ==External links== * http://www.engineering.com/Library/ArticlesPage/tabid/85/articleType/ArticleView/articleId/109/Centroids-of-Common-Shapes.aspx * http://www.efunda.com/math/areas/IndexArea.cfm 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「List of centroids」の詳細全文を読む スポンサード リンク
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