How do you find the general solutions for #cos (x)^4-sin (x)^4=2*cos (x)*cos(2x)#?
There are 6 solutions over the interval
I'll exclude the variable x for simplicity:
Now, we have 3 factors, when set equal to 0, will give us two unique solutions each for a total of 6 solutions over the interval
Again, the general solution is simply adding/subtracting multiples of
hope that helped