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# acosd

Inverse cosine in degrees

• 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.