1. Definition: A straight line is vertical if it is perpendicular to any straight line on the plane.

2. If a straight line is perpendicular to two intersecting straight lines on the plane, the surface of the straight line is vertical.

3. If one of two parallel straight lines is perpendicular to a plane, the other is also perpendicular to the plane.

4. The straight line is perpendicular to one of the two parallel planes and the other plane.

5. If two planes are perpendicular, the straight line perpendicular to their intersection on one plane is perpendicular to the other plane.

6. If two intersecting planes are perpendicular to the other plane, their intersection lines are also perpendicular to the other plane.

Extended data

Relevant certificates:

1, the point is out of plane

Let point p be any point outside plane α, and find the straight line PQ so that PQ⊥α.

Exercise:

① Draw a straight line L arbitrarily within α, with P as PA⊥l and vertical foot as A. ..

At this point, if PA⊥α, the required PQ has been made; If not,

(2) A in α is transmitted as m ⊥ L.

(3) PQ⊥m when passing P, and Q when hanging feet, then PQ is a straight line.

Prove:

Traditionally, l⊥PA, l⊥QA

∫PA∩QA = A

∴l⊥ aircraft PQA

∴PQ⊥l

∵PQ⊥m, and m∩l=A, m? α，l？ α

∴PQ⊥α

2. The point is on the plane

Let point p be any point on the plane α, and find the straight line PQ so that PQ⊥α.

Exercise:

① A point out of plane is AB⊥α, as shown above.

② P is PQ∨AB, and PQ is a straight line.

Prove:

According to property theorem 3, if AB⊥α and pq∨ab are given, then PQ⊥α.