二面角问题是立体几何三类求角问题中的难点.在求解二面角问题时,图中无两平面交线的无棱二面角更显困难.本文将以一道高考题为例,从不同的视角对此类无棱二面角的求解策略进行一些探讨.图1题目(2001年全国高考题)如图1,在底面是直角梯形的四棱锥S-ABCD中,∠ABC=90°,SA⊥面ABC The dihedral angle problem is a difficult point in the three-dimensional geometry problem. When solving the dihedral angle problem, the non-edge dihedral angles without the intersection of the two planes are more difficult. This article will take a college entrance examination question as an example. From a different perspective, we will discuss some of the strategies for solving such non-faceted dihedral angles. Figure 1 title (National College Entrance Examination Question in 2001) Figure 1. In a quadrangular pyramid S-ABCD with a right-angle trapezoid on the underside, ∠ABC=90 °, SA ⊥面ABC