Excel Function

ATAN(number)

Returns the arc-tangent of a number.

number

The number you want the arc-tangent of.

REMARKS

* The arc-tangent is the inverse of the TAN function.
* This function is also called the inverse tangent function.
* The "number" is the angle in radians.
* If "number" is not numeric, then #VALUE! is returned.
* The returned angle is given in radians between -PI/2 and PI/2.
* If your argument is in degrees, multiply it by PI/180 to convert it to radians.
* If you want to convert the result from radians to degrees, multiply it by 180/PI.
* You can use the TAN function to return the tangent.
* You can use the ACOS function to return the arc-cosine.
* You can use the ASIN function to return the arc-sine.
* You can use the DEGREES function to convert from radians to degrees.
* For a working example refer to the Trigonometric Functions page.
* For the Microsoft documentation refer to support.office.com

	A
1	=ATAN(0) = 0.00
2	=ATAN(1) = 0.785
3	=ATAN(-1) = -0.785
4	=ATAN(1)*180/PI() = 45
5	=DEGREES(ATAN(0.5)) = 27
6	=DEGREES(ATAN(1)) = 45
7	=ATAN(-50) = -1.551
8	=ATAN(TAN(0.5)) = 0.5
9	=ATAN(100) = 1.561
10	=ATAN(3/2)=ATAN2(2,3) = -1.000
11	=ATAN("some text") = #VALUE!

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5 - How many degrees is the arc-tangent of -0.5 radians.