On the cosine value of the angle between line and plane in space by vector For the problem of the angle between a line and a plane in space, can we first find the normal vector of a line, then find the normal vector of a surface, and then find the angle between two normal vectors, and then find the cosine of the angle complementary to the angle? Or do we first find the normal vector of the surface, and then find the angle between the normal vector and the line vector?

On the cosine value of the angle between line and plane in space by vector For the problem of the angle between a line and a plane in space, can we first find the normal vector of a line, then find the normal vector of a surface, and then find the angle between two normal vectors, and then find the cosine of the angle complementary to the angle? Or do we first find the normal vector of the surface, and then find the angle between the normal vector and the line vector?

First, find a normal vector of the plane,
If the line and the normal vector are an obtuse angle, minus 90 degrees is the answer. If the line and the normal vector are an acute angle, minus 90 degrees is also the answer
answer!