It was proved that the area coordinates of plane triangle element and the volume coordinates of tetrahedron element are equivalent to the oblique Cartesian coordinates by the analytical and geometrical methods.

• 本文通过分析法和几何法证明:在有限元法和边界元法中,平面三角形单元的面积坐标或四面体单元的体积坐标与由这些单元的二边或三边构成的斜交笛卡儿二维坐标或三维坐标,尽管定义不同,而其内容却是完全对等的。