i need help badly and quick

Can anyone sort this one out for me pleassseeeee......................................................................................Th e istantaneous current and voltage in an electric circuit are given by

i = I cos 50pi t

v = Vcos (50 pi t + pi/6)

determine an expression for the instantaneous power in the circuit, p = iv, as the sum of two cosines.

If I is 3mA and V is 5 V, calculate the maximum value of p, giving your answer in watts correct to three sig figures, and the first positive value of t at which it occurs.

I think you can follow, in part, the same steps that I described in the answer I gave to your previous post... The only difference is that, this time, you have a multiplication of variables instead of a summation. You can also use the GOAL-SEEK option but it is to be applied to the first derivate of p =i.v. This time, the result dp/dt must equal 0. Try to do it yourself.

Rui