The sine value of pi, denoted sin(pi), is 0. In trigonometry, we use pi (π) for 180 degrees to represent the angle in radians. Hence, sin pi is equal to sin 180 or sin π = 0. To find the value of sin(pi) using the unit circle, we can notice that the point that corresponds to pi on the unit circle is (-1, 0), which means that the sine of pi equals the y-coordinate of the point of intersection (-1, 0) of the unit circle and the line that forms an angle of pi with the positive x-axis. Since the y-coordinate of (-1, 0) is 0, the value of sin(pi) is 0.