This function takes the ratio of two sides of a right triangle and determines the corresponding angle, or arc tangent, in radians.
Atn(number)
Returns the arc tangent of a number.
The ratio is the length of the side opposite the angle divided by the length of the side adjacent to the angle. The range of the result is –pi/2 to pi/2 radians. To convert degrees to radians, multiply degrees by pi/180. To convert radians to degrees, multiply radians by 180/pi.
Atn is the inverse trigonometric of Tan, which takes an angle as its parameter and returns the ratio of two sides of a right triangle. Do not confuse Atn with the cotangent, which is the simple inverse of a tangent (1/tangent).