定理设△_i、V_i(i=1,2,3,4)表示四面体A_1A_2A_3A_4中,A_i对面旁切球的面积和体积,△_0和 V_0表示内切球面积和体积,则证明:(1)设 A_i 所对面外旁切球半径为 r_i,所对面面积为 S_i,内切球半径为 r_0,四面体体积为 V,则 The theorem is set as follows: △ _i, V_i (i = 1, 2, 3, 4) denote the area and volume of the side-cut ball opposite A_i in the tetrahedron A_1A_2A_3A_4, Δ_0 and V_0 denote the area and volume of the inscribed ball, ) Let A_i on the outer side of the cut ball radius r_i, the opposite side of the area S_i, the radius of the inscribed ball is r_0, tetrahedron volume V, then