# Learn =ACOS() function – How to use with Examples

`=ACOS()` is a mathematical function in Microsoft Excel that returns the arccosine of a number. The arccosine of a number is the angle, measured in radians, whose cosine is equal to the number. The function can be used to find the inverse cosine of a value, which is useful in various trigonometric calculations.

To use the `=ACOS()` function, simply enter the function in a cell and provide the number for which you want to find the arccosine as the argument. The argument must be between -1 and 1, inclusive.

### Examples of using the `=ACOS()` function:

1. `=ACOS(1)` returns 0, which is the arccosine of 1 in radians.
2. `=ACOS(-1)` returns 3.14159265358979, which is pi in radians.
3. `=ACOS(0.5)` returns 1.0471975511966, which is approximately 60 degrees in radians.
4. `=ACOS(-0.5)` returns 2.09439510239319, which is approximately 120 degrees in radians.
5. `=ACOS(0)` returns 1.5707963267949, which is pi/2 in radians.
6. `=DEGREES(ACOS(0.5))` returns 60, which is the arccosine of 0.5 in degrees.
7. `=RADIANS(ACOS(0.5))` returns 1.0471975511966, which is the arccosine of 0.5 in radians.
8. `=ACOS(SIN(1.57))` returns 1.57, which is pi/2 in radians.
9. `=ACOS(COS(1))` returns 1, which is pi/2 in radians.
10. `=ACOS(TAN(0.5))` returns 1.0471975511966, which is approximately 60 degrees in radians.

### Example of `=ACOS()` function by using VBA Macro:

Here’s an example of how to use the `=ACOS()` function in a VBA macro:

```Sub UseACosFunction()
Dim result As Double
result = Application.WorksheetFunction.Acos(0.5)
MsgBox result
End Sub```

Explanation: In this example, the `UseACosFunction` macro uses the `Application.WorksheetFunction.Acos` method to calculate the arccosine of 0.5. The result is stored in a variable named `result`, which is then displayed in a message box using the `MsgBox` function.

You can replace the argument in the `Acos` method with any value between -1 and 1, inclusive, to calculate the arccosine of a different number.

### Here are some additional tips for using the `=ACOS()` function in VBA:

1. Error handling: If the argument provided to the `Acos` method is outside the range of -1 to 1, the method will return an error. You can use error handling techniques in VBA, such as `On Error Resume Next` or `On Error Goto`, to catch and handle these errors in your macro.
2. Unit conversion: As mentioned earlier, the result of the `=ACOS()` function is expressed in radians. If you need to convert the result to degrees, you can use the `Application.WorksheetFunction.Degrees` method.
3. Chaining functions: You can use the `=ACOS()` function in combination with other functions in VBA. For example, you can calculate the cosine of an angle and then find the arccosine of the result to verify that the two values are equal.
4. Using variables: You can use variables in place of the argument in the `Acos` method. This allows you to easily change the value that is being used for the calculation.
5. Debugging: If you encounter an issue with the `=ACOS()` function in your macro, you can use the Debugger in the VBA editor to step through the code and identify the source of the problem.

### `=ACOS()`Similar functions include:

• `=ASIN()`: returns the arcsine of a number
• `=ATAN()`: returns the arctangent of a number
• `=COS()`: returns the cosine of a number
• `=SIN()`: returns the sine of a number
• `=TAN()`: returns the tangent of a number

### `=ACOS()` Function FAQs

What is the range of the argument for the `=ACOS()` function?

The argument for the `=ACOS()` function must be between -1 and 1, inclusive.

How is the result of the `=ACOS()` function expressed?

The result of the `=ACOS()` function is expressed in radians.

Can the result of the `=ACOS()` function be expressed in degrees?

Yes, the result of the `=ACOS()` function can be expressed in degrees by using the `=DEGREES()` function.

What is the difference between `=ACOS()` and `=COS()`?

The `=ACOS()` function returns the arccosine of a number, while the `=COS()` function returns the cosine of a number.

Can the `=ACOS()` function be used in a VBA macro?

Yes, the `=ACOS()` function can also be used in a VBA macro, as well as in a regular spreadsheet formula. To use it in a VBA macro, you can call the `Application.WorksheetFunction.Acos` method and provide the required argument. The result will be returned as a double-precision floating-point number.