Hello, I am using the trig diagram below and I am experiencing some problems. When I enter cos(100) in my calculator, i get a negative number. According to the graph, at 100 degrees going clockwise, cosine should be positive from 90 - 180 degrees. Can someone please explain what I am doing wrong.

Thanks.

http://mathscene.co.uk/t/F/Su36k02_m06.gif