Answer
(a) $V= 163cos(\frac{\pi}{2}-\omega t)$
(b) $163\ volt$, $t=\frac{1}{240}\ sec$
Work Step by Step
(a) Use the identity $sin\omega t=cos(\frac{\pi}{2}-\omega t)$, we have $V=163sin\omega t=163cos(\frac{\pi}{2}-\omega t)$
(b) For a maximum voltage of $163\ volt$, let $sin\omega t=1$, we have $120\pi t= \frac{\pi}{2}$, thus $t=\frac{1}{240}\ sec$
