Calculus (3rd Edition)

$\frac{3}{4}$
Recall that $\cdot= a_{1}a_{2}+b_{1}b_{2}$ Then, $\cdot<3,\frac{1}{2}>=\frac{1}{6}\times3+\frac{1}{2}\times\frac{1}{2}= \frac{3}{4}$