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Calculates the inverse of the tangent of a number in radians. The resulting angle is returned in radians. This function is most commonly used in engineering calculations that involve angular measurements.


Use the IMTAN formula with the syntax shown below, it has 1 required parameter:

  1. number (required):
    The angle for which the inverse tangent is to be calculated. Must be a real number or a reference to a cell containing a real number.


Here are a few example use cases that explain how to use the IMTAN formula in Google Sheets.

Calculate the angle of a right triangle

Given the length of two sides of a right triangle, use IMTAN to calculate the measure of the angle opposite the side of interest. This can be useful in engineering and construction projects.

Calculate bearing angles

In navigation, IMTAN can be used to calculate the bearing angle between two points on a map or chart.

Calculate the slope of terrain

When surveying land for construction, IMTAN can be used to calculate the slope of the terrain, which is important for determining the stability of the land.

Common Mistakes

IMTAN not working? Here are some common mistakes people make when using the IMTAN Google Sheets Formula:

Using the wrong form of the complex number

The IMTAN function requires the complex number to be in rectangular form. If you provide a polar form of the complex number, the function will return an error. Make sure you convert the polar form to rectangular form before using the IMTAN function.

Forgetting to divide the imaginary part by the real part

To find the inverse tangent of a complex number in rectangular form, you need to divide the imaginary part by the real part. If you forget to do this, the result will be incorrect.

The following functions are similar to IMTAN or are often used with it in a formula:

  • TAN

    The TAN function returns the tangent of an angle specified in radians. Tangent is the ratio of the length of the opposite side to the length of the adjacent side of a right-angled triangle. This function is commonly used in trigonometry and geometry calculations.

  • ATAN

    The ATAN function returns the arctangent of a value in radians, which is the angle whose tangent is a given value. This function is commonly used in trigonometry and geometry to calculate angles. The returned angle is in the range -π/2 to π/2.

  • ATAN2

    Returns the arctangent of the quotient of its arguments. ATAN2 is similar to ATAN, except that ATAN2 allows for two arguments and returns the angle of the result in the appropriate quadrant. This function is commonly used to calculate the angle between two points in a 2D plane. The angle is measured in radians and ranges from -pi to pi.


    The IMSIN function returns the sine of a complex number. The function takes a single parameter, which is a complex number in the form of a+bi. The function returns the sine of the complex number. This function is commonly used in engineering and scientific applications for analyzing waves and oscillations.

Learn More

You can learn more about the IMTAN Google Sheets function on Google Support.