คำตอบ - Trigonometry

The period of trigonometric functions is 360 degrees.

$$\cos \left(600°\right)=\cos \left(600-360°\right)$$

Subtracting one integer from another.

$$\cos \left(600-360°\right)=\cos \left(240°\right)$$

Reflecting the number with respect to 360 degrees.

$$\cos \left(240°\right)=\cos \left(360-120°\right)$$

The period of trigonometric functions is 360 degrees.

$$\cos \left(360-120°\right)=\cos \left(360-120-360°\right)$$

Removing or simplifying the same numbers on the top and bottom of a fraction.

$$\cos \left(360-120-360°\right)=\cos \left(-120°\right)$$

Computing the cosine of a negative angle.

$$\cos \left(-120°\right)=\cos \left(120°\right)$$

Reflecting the number with respect to 360 degrees.

$$\cos \left(120°\right)=\cos \left(180-60°\right)$$

Reflecting the cosine function with respect to 180 degrees.

$$\cos \left(180-60°\right)=-\cos \left(60°\right)$$

Computing the cosine of 60 degrees.

$$-\cos \left(60°\right)=-\frac{1}{2}$$