To model inheritance on a class diagram, a solid line is drawn from the child class (the class inheriting the behavior) with a closed, unfilled arrowhead (or triangle) pointing to the super class.
Color ring and a level section of A. H. Munsell color solid were analysed with regular triangle. Schemes for trigonal color design suitable for furniture design were suggested.
通过正三角形分析色环及孟赛尔色立体水平剖面，寻找三角色设计的配色方法，并应用于家具设计中。
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The solid is the polyhedron composed by the triangle faces.