# acosd

Inverse cosine in degrees

## Syntax

• ``Y = acosd(X)``

## Description

````Y = acosd(X)` returns the inverse cosine (cos-1) of the elements of `X` in degrees. The function's domain and range include complex values. For real elements of `X` in the domain [-1,1], `acosd` returns values in the range [0, 180]. For values of `X` outside this range, `acosd` returns complex values.```

## Examples

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### Inverse Cosine of 0

Verify that inverse cosine of 0 is exactly 90.

`acosd(0)`
```ans = 90```

### Round-Trip Calculation for Complex Angles

Show that the inverse cosine, followed by cosine, returns the original values of `X`.

```cosd(acosd([2 3])) ```
```ans = 2.0000 3.0000```

`acosd([2 3])` returns two complex angles, which are then passed to the `cosd` function. `cosd` returns the original values, `2` and `3`.

## Input Arguments

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### `X` — Cosine of anglescalar value | vector | matrix | N-D array

Cosine of angle, specified as a real-valued or complex-valued scalar, vector, matrix, or N-D array. The `acosd` operation is element-wise when `X` is non-scalar.

Data Types: `single` | `double`
Complex Number Support: Yes

## Output Arguments

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### `Y` — Angle in degreesscalar value | vector | matrix | N-D array

Angle in degrees, returned as a real-valued or complex-valued scalar, vector, matrix, or N-D array of the same size as `X`.