คำตอบ - Trigonometry

The period of trigonometric functions is 360 degrees.

$$\cos \left(3030°\right)=\cos \left(3030-360°\right)$$

Subtracting one integer from another.

$$\cos \left(3030-360°\right)=\cos \left(2670°\right)$$

The period of trigonometric functions is 360 degrees.

$$\cos \left(2670°\right)=\cos \left(2670-360°\right)$$

Subtracting one integer from another.

$$\cos \left(2670-360°\right)=\cos \left(2310°\right)$$

The period of trigonometric functions is 360 degrees.

$$\cos \left(2310°\right)=\cos \left(2310-360°\right)$$

Subtracting one integer from another.

$$\cos \left(2310-360°\right)=\cos \left(1950°\right)$$

The period of trigonometric functions is 360 degrees.

$$\cos \left(1950°\right)=\cos \left(1950-360°\right)$$

Subtracting one integer from another.

$$\cos \left(1950-360°\right)=\cos \left(1590°\right)$$

The period of trigonometric functions is 360 degrees.

$$\cos \left(1590°\right)=\cos \left(1590-360°\right)$$

Subtracting one integer from another.

$$\cos \left(1590-360°\right)=\cos \left(1230°\right)$$

The period of trigonometric functions is 360 degrees.

$$\cos \left(1230°\right)=\cos \left(1230-360°\right)$$

Subtracting one integer from another.

$$\cos \left(1230-360°\right)=\cos \left(870°\right)$$

The period of trigonometric functions is 360 degrees.

$$\cos \left(870°\right)=\cos \left(870-360°\right)$$

Subtracting one integer from another.

$$\cos \left(870-360°\right)=\cos \left(510°\right)$$

The period of trigonometric functions is 360 degrees.

$$\cos \left(510°\right)=\cos \left(510-360°\right)$$

Subtracting one integer from another.

$$\cos \left(510-360°\right)=\cos \left(150°\right)$$

Reflecting the number with respect to 360 degrees.

$$\cos \left(150°\right)=\cos \left(180-30°\right)$$

Reflecting the cosine function with respect to 180 degrees.

$$\cos \left(180-30°\right)=-\cos \left(30°\right)$$

Computing the cosine of 30 degrees.

$$-\cos \left(30°\right)=-\frac{\sqrt{3}}{2}$$