I think that some of them had heard them vaguely before. They also quickly realised that the same numbers would come up again with angles over 90. There was some initial confusion over whether they were positive or negative, but they were able to justify to each other and check using the unit circle. The different types of calculator posed a problem at first but eventually everyone was happily checking their results. Give out equipment.
Pupils copy axis from the board.
Discuss, whole class - patterns, same numbers going up and down etc. Pupils demonstrate, discuss. Hand waving, sketching on board. Use graphics calculator to show what curves look like. Pupil up to draw the triangle on the board, but not on the unit circle.