The vertical formula of two lines: k 1×k2=- 1. Perpendicular means that one line is at right angles to the other, and these two straight lines are perpendicular to each other. The symbol "⊥". "is usually used to indicate that there are two vectors A and B. a⊥b is necessary and sufficient if a b = 0, that is, (x 1x2+y 1y2)=0.

In mathematics, vectors (also known as Euclidean vectors, geometric vectors and vectors) refer to quantities with magnitude and direction. It can be imagined as a line segment with an arrow. The arrow indicates the direction of the vector; Line segment length: indicates the size of the vector.

The angle between the upward direction of a straight line and the positive direction of the X axis (called the inclination angle of the straight line) or the tangent of the angle (called the slope of the straight line) is often used to indicate the inclination degree of the straight line (for the X axis) on the plane.

Definition of two vertical lines:

Two straight lines are perpendicular to each other and do not necessarily intersect. Definition of verticality: verticality means that a straight line is at right angles to another straight line, and these two straight lines are perpendicular to each other. When the angle formed by the intersection of two straight lines (two straight lines that do not intersect each other at 90 degrees in solid geometry can also be called perpendicular to each other, which can be seen in version A of the compulsory textbook for senior high school) is a right angle, it is called perpendicular to each other.

When two straight lines intersect at right angles, they are perpendicular to each other, and one of them is perpendicular to the other. The intersection of these two straight lines is called vertical foot, two straight lines intersect two planes, or a straight line intersects a plane. If the angle of intersection is a right angle, it is called vertical.