Is the positive angle in mathematics a line rotating counterclockwise around the coordinate axis, is the negative angle rotating clockwise, and is that angle with the X axis or the Y axis? How do you know? Starting from the positive direction of coordinate axis X, rotate counterclockwise, and the angle is positive in the first and second quadrants. Rotate clockwise, and the fourth and third quadrant angles are negative.

Y=arcsinx domain x∈[- 1, 1], range y∈[-π/2, π/2]

Y=arccosx domain x∈[- 1, 1], range y∈[-π/2, π/2]

Y = the arc tangent domain x∈[-∞, +∞], and the range y∈(-π/2, π/2).

Remember the image of the function.