คำตอบ - Trigonometry

Reflecting the number with respect to 360 degrees.

$$\sin \left(310°\right)=\sin \left(360-50°\right)$$

The period of trigonometric functions is 360 degrees.

$$\sin \left(360-50°\right)=\sin \left(360-50-360°\right)$$

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

$$\sin \left(360-50-360°\right)=\sin \left(-50°\right)$$

Computing the sine of a negative angle.

$$\sin \left(-50°\right)=-\sin \left(50°\right)$$