[quote=Qwertyuiop23;514674]Today I was having a bit of a nostalgia moment when I came across an old problem then when I tried to solve it...well lets say it was harder than it seemed.

Anyway the equation was:

And it asked you to find the general form of the solution...

I have tried compound, double angle formulas but to no avail. I can graph it and find some solutions but not how to find a general form equation? Can someone please shoe me how to solve it?

Cheers

Lance

cos(x) = -sin(3x) = cos(π/2 + 3χ)

π/2 + 3x = 2nπ + or - ( x)

Now solve for x .