Guys, I am in Calculus 2, but I still have trouble seeing the answer when u plug in a radian measure into a trig function. My teacher assumes we know the answer right away. I know Sin(0)= 0 and Cos(0)=1, but that's about it. I don't know things like Sin(pi/2) I have to input it into the calculator. How do I find this out, or memorize it. Is it from the Unit Circle? And if not what should I refer to to memorize these values. Also, how do u use the Unit Circle, what information does it give you? Thanks for your time.