Help with Trigonometry. Addition and Subtraction.?

Find a unit circle and there you will see that sin 45 = (sqrt2)/2. Your calculator is more of a pain for you than help, so I wouldn't use it at all for these conversions. You did good in recognizing the need to use trig identities. This is basically a cos (alpha-beta) problem. Use the trig identity and your unit circle and you should get the right answer.