ATAN2

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_num, y_num). The angle is given in radians between -pi and pi, excluding -pi.

Syntax

ATAN2(x_num,y_num)

X_num     is the x-coordinate of the point.

Y_num     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.
  • If both x_num and y_num are 0, ATAN2 returns the #DIV/0! error value.
  • To express the arctangent in degrees, multiply the result by 180/PI( ) or use the DEGREES function.

Example

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Selecting an example from Help

Selecting an example from Help
  • Press CTRL+C.
  • In the worksheet, select cell A1, and press CTRL+V.
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Formula Description (Result)
=ATAN2(1, 1) Arctangent of the point 1,1 in radians, pi/4 (0.785398)
=ATAN2(-1, -1) Arctangent of the point -1,-1 in radians, -3*pi/4 (-2.35619)
=ATAN2(-1, -1)*180/PI() Arctangent of the point 1,1 in degrees (-135)
=DEGREES(ATAN2(-1, -1)) Arctangent of the point 1,1 in degrees (-135)
 
 
Applies to:
Excel 2003