This may not even count as a calculus question, simply because I've already done the calculus part. I just don't know how to do the algebra to solve it haha. So if this needs to be moved, I apologize.

Anyway! Here is the problem and what I've done:

Problem:An electric current, I, in amps, is given by where C /= 0 is a constant. Find the minimum and maximum values of I. For what values of t will these occur if .

My work:

I know how to find the max and min values. I took the derivative, set it to 0, and began solving for t.

Factored out a c and got:

So...how do I solve for t from this point? Do I use the arccosine and arcsine? I'm not sure...I just can't seem to remember how to do it!

Thanks for any help!