Gradients of Perpendicular Lines Investigation

A ready-made Autograph file to dynamically demonstrate how the gradients of perpendicular lines alter as the graphs move. Students can note down on the attached accompanying worksheet different pairs of gradients found, then find that the product is always -1. They can finish off by researching the relationship between the gradients - that they are negative reciprocals of each other. This mini investigation sheet can then be stuck into exercise books / notes to summarise the key points of this topic.