## Trigonometry (10th Edition)

$t = 0.2015~s$
We can find the least value of $t$ such that $V = 0.30$: $V = cos~2\pi~t$ $cos~2\pi~t = 0.30$ $2\pi~t = arccos(0.30)$ $2\pi~t = 1.266$ $t = \frac{1.266}{2\pi}$ $t = 0.2015~s$