Answer
$V = (30~sin~120~\pi t)+(40~cos~120~\pi t)$
We can see a sketch of the graph of this function below:
Work Step by Step
$V = V_1+V_2$
$V = (30~sin~120~\pi t)+(40~cos~120~\pi t)$
We can see a sketch of the graph of this function below: