文[1][3]对三角形内心,旁心的性质进行了研究,文[4]给出了四面体内心与旁心的一个有趣性质,笔者深受启发,探究出空间四面体内心和旁心的另外两个性质,为行文方便,我们把文[4]的两个结论作为本文的两个引理.引理1设四面体ABCD的四个顶点A,B,C,D所对的三角形面积分别为SA,SB,SC,S The paper[1][3] studied the nature of the inner and the inner side of the triangle. The article[4] gives an interesting property of the inner and inner sides of the tetrahedron. The author was inspired to explore the inner and outer sides of the inner and outer sides of the triangle. The other two properties of the mind are for convenience. We use the two conclusions of [4] as two lemmas in this paper. Lemma 1 Let the four vertices of the tetrahedron ABCD be A, B, C, and D. The triangle area is SA, SB, SC, S, respectively