1. The problem is to find the correct values of $\cos 120^\circ$ and $\sin 120^\circ$ among the given options. 2. Recall that $120^\circ$ is in the second quadrant where cosine is negative and sine is positive. 3. The exact values are: $$\cos 120^\circ = -\frac{1}{2}$$ $$\sin 120^\circ = \frac{\sqrt{3}}{2}$$ 4. Therefore, the correct statement is: $$\cos 120^\circ = -\frac{1}{2},\ \sin 120^\circ = \frac{\sqrt{3}}{2}$$ 5. The other options are incorrect because they assign wrong signs or wrong values. 6. So the correct answer is the first line given by the user.