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Atan2

ATAN2 Function

The ATAN2 function in Excel returns the arctangent of the quotient of its arguments, in radians between -π and π. It provides the angle theta of an (x, y) point, giving a result from 0 to 2π.

Unlike the ATAN function, which only takes one argument, ATAN2 takes two arguments. It's useful because it considers the signs of both arguments, distinguishing between, for example, angles in the first and third quadrants.

Syntax:

ATAN2(x_num, y_num)
  • x_num: The x-coordinate.
  • y_num: The y-coordinate.

Examples:

  1. =ATAN2(1, 1) would return a value in radians, approximately 0.7854 (or 45° when converted to degrees), as this is the angle corresponding to the point (1,1) in the first quadrant.
  2. =ATAN2(-1, -1) would return approximately -2.3562 radians (or -135°), representing the third quadrant.
  3. =ATAN2(A1, A2) would return the arctangent based on the x and y values in cells A1 and A2, respectively.

Note: If you want the result in degrees rather than radians, you can use the formula =DEGREES(ATAN2(x_num, y_num)).