1. If two planes are perpendicular, the line perpendicular to the intersection in one plane is perpendicular to the other plane.

2. If two planes are perpendicular, the straight line perpendicular to one plane is parallel to or in another plane.

plane

The locus of a point with equal distance between two points in space. In analytic geometry, the plane formula is A*(x-x0)+B*(y-y0)+C*(z-z0)=0, which is defined as the set of all points whose lines with fixed points (x0, y0, z0) are perpendicular to the fixed direction (a, b, c). These two definitions are consistent in mathematics.