My teacher said the only ones we need to know Is Theorem 11,12 and 19. But other people on here are saying different ones?
The theorems that you should learn are 9,14 and maybe 19, but 19 came up last year. You should really also look over the other triangle related ones, just in case.
Try and focus on Pythagoras and The parallelogram though as those are by far the most likely to come up.
you need to know 4,6,9,14,19