当平面对三个坐标面都成倾斜时称为空间任意平面,简称为空间平面(图1)。空间平面可由空间不在一直线上的三个点,或两相交直线,或一对平行直线来确定其空间位置。表示空间任意平面的常用形式有两种,一种是用两投影角来表示(图2),另一种是用一投影角和相应的两面角来确定(图3)。 When the plane is tilted on all three coordinate surfaces, it is called any plane of space, which is simply referred to as the space plane (Figure 1). The space plane can be determined by three points where the space is not in line, or two intersecting lines, or a pair of parallel lines to determine its spatial position. There are two common forms for expressing an arbitrary plane in space, one is represented by two projection angles (Figure 2), and the other is determined by a projection angle and the corresponding dihedral angle (Figure 3).