Perpendicular Lines
Two lines are perpendicular to each other if they meet at a right angle (\(90\) degrees). We can see examples of perpendicular lines everywhere, where walls meet the floor, in grids and the corners of paper. An example of two perpendicular lines is shown in the image below.
How can we tell if two lines are perpendicular? We can measure the angle that the two lines meet at, and check if this is a right angle. Children could try this by tearing the corner off a sheet of paper and holding it up to different pairs of lines found around the classroom. A demonstration of this is shown in the image below.
We can also check whether two lines are perpendicular by considering the gradients of the lines.If you are unfamiliar with the gradients of lines, you can learn about them here. If the gradients of two lines multiply to be \(-1\), then the two lines are perpendicular.
Another pair of lines that are defined by their gradient are parallel lines. To learn more about parallel lines, you can read our article on them.
