The value of 0 in this equation is the angle in radians. In mathematics, the trigonometric functions such as sine and cosine are defined in terms of angles. In this equation, cos(y) = sin(0), the value of 0 represents an angle of 0 radians, which is commonly used as a reference angle in trigonometry. It's important to note that the sine of 0 radians is equal to 0, and the cosine of 0 radians is equal to 1.