The Excel ATAN function returns the inverse tangent or arc-tangent of a number. In geometric terms, the function returns the angle of a right-triangle given the ratio of its opposite side over its adjacent side. The ATAN function is the inverse of the TAN function

**Syntax**: =ATAN(number)

The ATAN function syntax has the following arguments:

**Number**(Required): The tangent of the angle you want.

**Example**: Let’s look at some Excel ATAN function examples and explore how to use the ATAN function as a worksheet function in Microsoft Excel:

**Syntax**: =ATAN(G26)

**Result**:

Based on the Excel spreadsheet above, the following ATAN examples would return:

**Syntax**: =ATAN(G27)

**Result**: 1.434657366

**Syntax**: =ATAN(G28)

**Result**: 1.428899272

**Syntax**: =ATAN(G29)

**Result**: -1.56079666

**Syntax**: =ATAN(G30)

**Result**: 0.5404195

**Syntax**: =ATAN(G31)

**Result**: -0.109559527

**Syntax**: =ATAN(G32)

**Result**: 0.785398163