Chapter 3, Problem 35P

Two vectors, $\stackrel{\to }{r}$ and $\stackrel{\to }{s}$, lie in the xy plane. Their magnitudes are 4.50 and 7.30 units, respectively, and their directions are 320° and 85.0°, respectively, as measured counterclockwise from the positive x axis. What are the values of (a) $\stackrel{\to }{r}$ · $\stackrel{\to }{s}$ and (b) $\stackrel{\to }{r}$ × $\stackrel{\to }{s}$?