ATAN2

Description: Returns the arctangent, or inverse tangent, of the specified x- and y-coordinates. The arctangent is the angle from the x-axis to a line containing the origin (0, 0) and a point with coordinates (x_Number, y_Number). The angle is given in radians between -pi and pi, excluding -pi.

Syntax: ATAN2(x_Number, y_Number)

x_Number is the x-coordinate of the point.
y_Number is the y-coordinate of the point.

Remarks:

A positive result represents a counterclockwise angle from the x-axis; a negative result represents a clockwise angle.
ATAN2(a,b) equals ATAN(b/a), except that a can equal 0 in ATAN2.
Both x_Number and y_Number cannot be 0.
To express the arctangent in degrees, multiply the result by 180/PI or use the DEGREES function.

Example:

ATAN2(1, 1) = 0.785398 [the arctangent of the point (1,1) in radians, pi/4]