The term "perpendicular" means that two objects make an angle of 90° between them.
For example, if two segments are perpendicular, the angles created in the intersection point are equal to 90°:
If we have two linear equations y = m1x + b1 and y = m2x + b2 and these lines are perpendiculars, the slopes m1 and m2 have the following relation:
[tex]m_1=-\frac{1}{m_2}[/tex]
In the same way, if a line is perpendicular to a plane, the intersection point has an angle of 90°:
