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众所周知,要计算二面角的大小只要作出它的平面角并计算出它的大小就可以了。在一般情况下,二面角的平面角是很容易作出来的。但在某些情况下,二面角的平面角却并不容易作出来,或者作了出来,计算却相当困难,因而不能顺利求出二面角的大小。为解决这一问题,在教学中作了如下尝试。方法一在平面几何中,若两条平行直线和第三条直线相交,则其同位角相等,内错角相等。在立体几何中有类似的结论:若两个平行平面和第三个平面相交,则位于相同位置
As we all know, to calculate the size of the dihedral angle just make its plane angle and calculate its size on it. In general, the dihedral plane angle is very easy to make. However, in some cases, the dihedral angle is not easy to make, or when it is calculated, it is quite difficult to calculate the dihedral angle. To solve this problem, made the following attempts in teaching. Method One In plane geometry, if two parallel straight lines and the third straight line intersect, the same phase angle, the same error within the angle. In solid geometry there is a similar conclusion: if two parallel planes intersect the third one, then they are in the same position