I have a homework problem that I don't know what to do with. We were just introduced to sum and difference identities. We've always been provided values in degrees both in class and in homework until this problem. I checked the book to see if a similar problem had been worked out; it hadn't. Any help would be appreciated.
Use the information below to find the exact value of sin (A-B): $\cos A = \dfrac1{3}, 0 < A < \dfrac{\pi}{2}, \sin B = -\dfrac1{2}, \dfrac{3\pi}{2} < B < 2\pi$