ATAN

Syntax: ATAN(X)

X = a numeric value expressed in radians.

ATAN returns the 2-quadrant arc tangent of angle X. The result is the angle (in radians) whose tangent is X and ranges from $-\pi/2$ to $\pi/2$. To convert radians to degrees, use the DEGREES function.

Examples:

ATAN(.5) = 0.463647609

ATAN(J44) = -0.785398163, where J44 = -1

DEGREES(ATAN(U6)) = 87.70939, where U6 = 25

Excel function: ATAN