# Math.acos()

#### Availability

Flash Player 5. In Flash Player 4, the methods and properties of the Math object are emulated using approximations and may not be as accurate as the non-emulated math functions supported by Flash Player 5.

#### Usage

    Math.acos(x)

#### Parameters

`x` A number from -1.0 to 1.0.

#### Returns

Nothing.

#### Description

Method; computes and returns the arc cosine of the number specified in the parameter `x`, in radians.