论文部分内容阅读
《立体几何》（全一册）117页第3题（如图1）有这样的结论：cosθ=cosθ1cosθ2若设则该结论可改写为即二面角（A—BC——D）一个而内，从棱上一点出发的射线与另一个面所成角的正弦等于这条射线与棱所成角的正弦和该二面角的平面角的正弦的乘积．这一公式反映了立体几何?..
“Solid Geometry” (a full volume) 117 pages 3 (as shown in Figure 1) has this conclusion: cosθ = cosθ1cosθ2 If set then the conclusion can be rewritten as dihedral angle (A-BC - D) and within The sine of the angle formed by a ray starting from a point on the edge and the other side is equal to the product of the sine of the angle formed by this ray and the edge and the sine of the plane angle of the dihedral angle. This formula reflects the solid geometry..