问题空间两条异面直线a、b所成角为α,过空间一定点P与a、b所成角的是θ的直线l有多少条?为要弄清这个问题,可先看下面两个结论:结论1从一个角的顶点引这个角所在平面的斜射线,使斜射线和这个角两边的夹角相等,则斜线在平面内的射影是这个角的平分线所在的直线.结论2直线AB与平 The angle between the two opposite straight lines a and b of the problem space is α, and the number of the straight line l that makes the angle between the point P and the a and b over the space is θ? To find out the problem, first look at the following two Conclusions: Conclusion 1 From the vertex of an angle, the oblique ray of the plane in which the angle lies is set so that the angle between the oblique ray and the two sides of this angle is equal, then the projection of the slash in the plane is the straight line where the bisector of this angle lies. 2 straight lines AB and flat