$\vec A$ has the magnitude $13.5$ m and is angled $68.0°$ counterclockwise from the positive direction of the x axis of an xy coordinate system. Also, $\vec B$ $= (11.5 m)i + (7.15 m)j$ on that same coordinate system. We now rotate the system counterclockwise about the origin by $20.0°$ to form an $x'y'$ system.
(a) On this new system, what are $\vec A$ and $\vec B$ in unit-vector notation?
I don't understand what needs to be done.
Am I supposed to:
$13.5$ times $68$ times cos minus $20$ ?
$\sqrt 11.5^2 + 7.15 ^2 - 20$?