Identifying Perpendicular Lines: Finding 90-Degree Intersections

Question

Which lines are perpendicular to each other?

00:03 Are any of these lines perpendicular?

00:06 Perpendicular lines meet to form a right angle, exactly ninety degrees.

00:12 In this example, the angle is less than ninety degrees, so they are not perpendicular.

00:26 And here, the lines don't meet at all, also not perpendicular.

00:30 And that's how you know which lines are perpendicular!

Let's remember that perpendicular lines are lines that form an angle of 90 degrees between them.

In each of the answers, we will draw the letter T at the point of intersection of the lines.

Let's examine figure A:

We notice that the lines do form a right angle and the lines are perpendicular to each other.

Let's examine figure B:

We notice that the lines do not meet and do not form any angle; therefore, they are parallel lines and not perpendicular.