Y, I hope you are satisfied. If not, there must be two situations in your math book. A, m, p, q are represented by point coordinates.

3, Z axis, establish a coordinate system.

2。

2:

1, a few pages should be enough. See for yourself):

1. With A as the origin and three mutually perpendicular sides as X, the positional relationship between the two straight lines is very special. Just calculate the cosine of the angle between vector pq and am. This problem is zero, and the other straight line is just perpendicular to this plane, so no matter how the straight line in the plane moves, of course, the two straight lines are perpendicular.

Regarding your second question, if this problem occurs in solid geometry, for example, a straight line is perpendicular to am in a plane.

The method of solving the problem is as follows (using space vector to solve, I don't know if you have learned it. Using space vector, you will find that the cosine of the angle between two straight lines has nothing to do with the parameters after the straight lines are expressed by parameters. This is the most commonly used method, and the situation mentioned above is rare.

Well, that's my answer. I come from Jiangsu.