Microsoft® Excel® 2010 Formulas & Functions Inside Out

ATAN()

Syntax. ATAN(number)

Definition. This function returns the arctangent or inverse tangent of a number.

Argument

• number (required) The tangent of the angle you want to calculate

Background. Use the ATAN() function to calculate the adjacent angle based on the tangent (see Figure 16-7). In other words, the arctangent is the angle whose tangent is number. The result is a radian measure between –π/2 and π/2 and has to be converted into degrees with the DEGREES() function or by multiplying the result with 180/PI().

Because each angle occurs two times in a full circle, the value range for an arctangent is restricted.

• If the angle is calculated as a radian measure, the value range spans –π/2 to π/2.

• If the angle is calculated in degrees, the value range ...