Tentukan nilai x yg mempunyai pers 2 cos^ x- sin x -1=1 untuk 0

[tex]2 \cos^{2} (x) - \sin(x) - 1 = 1 \\ 2(1 - \sin^{2} (x) ) - \sin(x) - 2 = 0 \\ 2 -2 \sin^{2} (x) - \sin(x) - 2 = 0 \\ 2 \sin^{2} (x) + \sin(x) = 0 \\ \sin(x) (2 \sin(x) + 1) = 0 \\ \sin(x) = 0 \\ atau \\ 2 \sin(x) = - 1 \\ \sin(x) = - \frac{1}{2} [/tex]
Jadi nilai x yang memenuhi:
[tex] {0}^{0} , {180}^{0} , {210}^{0} , {300}^{0} ,{360}^{0}[/tex]