ATAN
Returns the arctangent (inverse tangent) of a number. The result is an angle in radians between -PI/2 and PI/2.
ATAN(number)Arguments
numberThe tangent value (any real number)
=ATAN(1)Arctangent of 1 = PI/4 radians (45 degrees)
=DEGREES(ATAN(1))Arctangent of 1 = 45 degrees
=ATAN(0)Arctangent of 0 = 0 radians
- •Accepts any real number (no range restriction like ASIN/ACOS)
- •Returns radians, wrap in DEGREES() for degrees
- •Use ATAN2(x,y) for two-argument version
- •Expecting ATAN to return an answer in degrees - it always returns radians, so the result often needs to be wrapped in DEGREES to be useful
- •Using ATAN instead of ATAN2 when both an x and y coordinate are available - ATAN only takes a single ratio and can't distinguish between angles in different quadrants, while ATAN2 handles that correctly
- •Confusing ATAN with TAN - ATAN takes a ratio and returns an angle, while TAN takes an angle and returns a ratio, and using the wrong one inverts the intended calculation
TANPerforms the inverse operation - takes an angle and returns a tangent ratio, rather than taking a ratio and returning an angle.ATAN2Calculates an angle from separate x and y coordinates, correctly handling all four quadrants in a way plain ATAN cannot.DEGREESConverts ATAN's radian result into degrees, a common step since ATAN never returns degrees directly.Does ATAN return degrees or radians?
Always radians. Wrap the result in DEGREES, like DEGREES(ATAN(1)), if you need degrees instead.
Why should I use ATAN2 instead of ATAN?
ATAN only accepts a single ratio and can't tell which quadrant the angle belongs in, while ATAN2 takes separate x and y coordinates and correctly determines the angle across all four quadrants.
What's the difference between ATAN and TAN?
ATAN takes a ratio and returns the corresponding angle. TAN does the opposite - it takes an angle and returns a ratio.
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