Math & Trig
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=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.
Applies To:
Excel for Microsoft 365Excel for Microsoft 365 for MacExcel 2024Excel 2024 for MacExcel 2021Excel 2021 for MacExcel 2019Excel 2016
=ATAN2(x_num, y_num)
Hover argument names in the table for details.
Output typeNumber
Popularity38 / 100
VolatileNo
Dynamic ArrayNo
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◧ Arguments
| Argument | Type | Required | Description |
|---|---|---|---|
x_num |
Number | Required | The x-coordinate of the point. |
y_num |
Number | Required | The y-coordinate of the point. |
▣ Examples
Arctangent of the point 1,1 in radians, pi/4
=ATAN2(1, 1)
Result:
0.785398163
Arctangent of the point -1,-1 in radians, -3*pi/4
=ATAN2(-1, -1)
Result:
-2.35619449
Arctangent of the point 1,1 in degrees
=ATAN2(-1, -1)*180/PI()
Result:
-135
Arctangent of the point 1,1 in degrees
=DEGREES(ATAN2(-1, -1))
Result:
-135
§ 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.
✦ Tips
- 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.
- To express the arctangent in degrees, multiply the result by 180/PI( ) or use the DEGREES function.
⚠ Common Errors
#DIV/0!
If both x_num and y_num are 0, ATAN2 returns the #DIV/0! error value.
Fix: At least one must be nonzero
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