Mathematically, the plane rectangular coordinate takes the longitudinal axis as the Y axis, which is positive upward from the origin and negative downward; Taking the horizontal axis as the X axis, it is positive to the right and negative to the left from the origin; Quadrants are numbered counterclockwise. The longitudinal axis of the plane rectangular coordinate system in the north-south direction is the X axis, which is positive from the origin to the north and negative from the south. Taking the horizontal axis of the east-west direction as the Y axis, it is positive from the origin to the east and negative from the west; Quadrants are numbered clockwise.

In measurement, the angle value is calculated clockwise based on the north direction, and in mathematics, the angle value is calculated counterclockwise based on the horizontal axis. After the X-axis and Y-axis are interchanged vertically and horizontally, all trigonometric formulas in mathematics can also be directly applied to measurement without any changes.