The IMTAN function returns the tangent of a complex number in x + yi or x + yj text format. The tangent of a complex number is calculated by the following formula:
Syntax:= IMTAN (inumber)
The IMTAN function syntax has the following arguments:
 Inumber: Required. A complex number for which you want the tangent
Example: Let’s look at some Excel IMTAN function examples and explore how to use the IMTAN function as a worksheet function in Microsoft Excel:
Syntax: =IMTAN(A2)
Result:
Based on the Excel spreadsheet above, the following IMTAN examples would return:
Syntax: =IMTAN(A3)
Result: 0.03381282607989671.01479361614663i
Syntax: =IMTAN(A4)
Result: 1.6343988925314E080.999999974296243i
Syntax: =IMTAN(A5)
Result: 0.2370138309162710.896437917127862i
Syntax: =IMTAN(A6)
Result: 0.00490825806749606+1.00070953606723i
Syntax: =IMTAN(A7)
Result: i
Syntax: =IMTAN(A8)
Result: 0.2735530828073071.0028105075835i
Syntax: =IMTAN(A9)
Result: 0.0000898347764697156+1.00001320743478i
Syntax: =IMTAN(A10)
Result: 2.99350606711029E100.999999999529219i
Syntax: =IMTAN(A11)
Result: 4.10750577733132E111.00000000006335i
Syntax: =IMTAN(A12)
Result: 7.75702968155393E18j
Syntax: =IMTAN(A13)
Result: 2.57039272660676E21+i
Note:
 Use COMPLEX to convert real and imaginary coefficients into a complex number.
 If inumber is a value that is not in the x+yi or x+yj text format, IMTAN returns the #NUM! error value.

If inumber is a logical value, IMTAN returns the #VALUE! error value.