## Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)

(a) $A \cdot B = -18$ (b) $A \cdot B = 10$
We can use the formula for the dot product of two vectors $A$ and $B$: $A\cdot B = A_x~B_x + A_y~B_y$ (a) $A \cdot B = A_x~B_x + A_y~B_y$ $A \cdot B = (3)(2)+(4)(-6)$ $A \cdot B = -18$ (b) $A \cdot B = A_x~B_x + A_y~B_y$ $A \cdot B = (3)(6)+(-2)(4)$ $A \cdot B = 10$