Head Start Lectures: Mathematics Extension 2 Handout (January 2018)

Just like last time, this version of the handout contains full worked solutions to every question, including those we didn't get to cover. I had a FAQ in what I did after e(PM + PM'). PM and PM' are distances, so when I do PM + PM' I'm really just combining the distances together. If you look at the diagram, that's where I get MM' from. Then the reason why the distance MM' is 2a/e is because if you think about it, the directrix is literally a/e units away from the y-axis. So the distance between both of them is just double that, i.e. 2a/e.