Given that the motion of an object is given by v(t) = $\displaystyle 1-\sin\(t-\frac{\pi}{4})$, where t is in seconds. Find the maximum velocity of the object for the first four seconds.

I know maximum velocity would mean acceleration =0. So I differentiated v(t), and equated it to 0, but I do not really know what to do next..

Thank you for your help!