This is another video in the Year 9 series looking at Linear Relations. Parallel and perpendicular lines are pretty important and can trick a lot of people. In this video I look at what makes two or more lines parallel (they have the same gradient) and how the gradients of two perpendicular lines are related. I show how we can find the gradients of parallel and perpendicular lines as well as find equations of parallel and perpendicular lines. There are lots of worked examples and the theory is explained in an easy to understand way.