Learn how to find equations of parallel lines, work out the gradient of perpendicular lines, and prove that given lines are parallel or perpendicular.

I need a solution for three dimensions. This is not an assignment and I've been through google without success. I'm sure I have a book laying around with the answer, but I can't seem to find it.

Lines Squared Nanoleaf If you already have Lines, and are just looking to add some perpendicular geometry, Lines Squared are fully compatible with your current kit.