hey first of all, that s not an equation, i dont know the word in english (sorry) but here... i have to solve that in the interval [-2pi , pi ] cos(2x)-√3sin(2x) ≥ -√2 here is what i did..... 2(.5cos(2x)-√3 /2 sin(2x) ≥ -√2 cos(pi/3)cos(2x)-sin(pi/3)sin(2x) ≥ -√2 /2 cos(pi/3 + 2x) ≥ -√2 / 2 and that s gonna be.... pi/3 + 2x ≥ pi/4 x ≥ -pi/24 now what, is that all what i have to do? is waht i did right? and finally, what should the solution to this 'problem' be ???? thanks!