This is an incredibly incisive resource where Pythagoras in circles has been established as being about 3 key cases, which each column focusing on a different strategy. The problems have been decontextualised to help the learner attend to the key feature. Further the the radius has been stated, but not marked on. Experience of use in class has been that having completed this task learners found past examination papers to be trivial. Variation in the orientation in the bottom row of problems is a subtle, but important twist.