Respuesta :

Given the expression;

cos x = -1/2

Take the cos inverse of both sides;

[tex]\begin{gathered} \text{cos}^{-1}(\cos x)=cos^{-1}(-\frac{1}{2}) \\ x\text{ = }cos^{-1}(-\frac{1}{2}) \\ x=-60^0 \end{gathered}[/tex]

Since cos is negative in the s