Which quadrants show sine as a positive function?

In the context of the unit circle and trigonometric functions, the sine function corresponds to the y-coordinate of a point on the unit circle. The y-coordinate is positive when the angle is in the first and second quadrants.

In the first quadrant (0 to 90 degrees or 0 to π/2 radians), both the x and y coordinates are positive, so the sine is also positive. In the second quadrant (90 to 180 degrees or π/2 to π radians), the x-coordinate is negative while the y-coordinate remains positive, which means sine continues to be positive.

In the third quadrant (180 to 270 degrees or π to 3π/2 radians), both x and y coordinates are negative, making the sine function negative. Similarly, in the fourth quadrant (270 to 360 degrees or 3π/2 to 2π radians), the x-coordinate is positive while the y-coordinate is negative, which leads to a negative sine value.

Thus, sine is positive specifically in the first and second quadrants. This understanding directly points to the option that indicates the quadrants where sine functions positively—those being the first and second quadrants.