We're very much the same as this. Set 1 cover the full course. Set 2 for us is a sort of mixed set of students studying bits of the higher but not the whole course. Some of these students will eventually sit foundation.

I've had students say "I thought I understood compound interest but that formula really confused me"

Depends how it's aligned on the axes I guess. Also an interesting case if the trapezium is one with 2 "positive but different gradient" sides as opposed to "one positive, one negative gradient sides". Realise that's a terrible explanation but hope it makes sense.

Surely only true to you rotate an isosceles trapezium around an axis.