Is there a more rigid definition for perpendicularity? A line of the form y = C has a slope of 0. There is no negative reciprocal for 0, but a line of the form x = C is still perpendicular.

Parallel lines never intersect, and perpendicular lines intersect at a 90 degree angle. Learn how to identify parallel and perpendicular lines.

Given line A and point P, Sal finds the equation of the line perpendicular to A that passes through P. Created by Sal Khan and Monterey Institute for Technology and Education.

Review the basics of parallel and perpendicular lines. Identify and draw parallel and perpendicular lines in some practice problems.

Parallel lines are lines that never intersect, and they form the same angle when they cross another line. Perpendicular lines intersect at a 90-degree angle, forming a square corner. We can identify these …

Parallel lines are lines that never intersect, and they form the same angle when they cross another line. Perpendicular lines intersect at a 90-degree angle, forming a square corner. We can identify these …

In this video, we first derive the conditions for parallel and perpendicular lines. We then apply these conditons to prove that given lines are parallel/perpendicular.

The slopes of parallel lines are equal, and the slopes of perpendicular lines are opposite reciprocals. This is a worked example of determining whether given lines are parallel or perpendicular.

Since there's no "change in x" (but y can take on any value), the line is vertical. In order to write its equation, all we need to know is where it crosses the X-axis and we call that point c, giving us the …

Sal constructs a line perpendicular to a given line through a point on the line using compass and straightedge. Created by Sal Khan.