Find the equation of the tangent line to the graph

Hi everyone. I'm working on a calc problem, but I found it to be difficult. Maybe I'm missing the point.

Find the equation of the tangent line to the graph of

Well, this is the derivative I got:

Since it just says the equation of the line, but it doesn't specify an x-value, so I just plug in a random value. However, I found it extremely difficult to do it the regular way, because trig functions are involved.

Is there a trick to solve this problem?

Thanks a lot.