Perpendicular lines are two straight lines that intersect at a 90-degree angle, forming right angles at their point of intersection.
In a Cartesian coordinate system, where lines are represented graphically, perpendicular lines have slopes that are negative reciprocals of each other.
For example, if one line has a slope of 2, a perpendicular line to it would have a slope of -1/2.
Perpendicular lines are important in geometry and trigonometry and are used to describe relationships between lines, angles, and shapes in various mathematical and real-world contexts.