三角形面积公式的行列式版本
http://wenku.baidu.com/link?url=CA7llUzU7NPsdHzeK1-95ZPJIuy93avlHVx8mKIjO1Pb5qz_NaZ467eRIGY6TBdLWsVCNnI3As3sfwhyEkOsZp0iyn6vPzdYqZdCotlFgHi
混合积和四面体体积
http://en.wikipedia.org/wiki/Triple_product
http://www.nabla.hr/Z_MemoHU-020.htm
http://www.vitutor.com/geometry/vectors/tiple_product.html