PHP Function: acos

In PHP, the acos function is used to calculate the arc cosine of a number. It returns the inverse cosine of a value, which is the angle in radians whose cosine is equal to the specified number.

Syntax

The syntax for the acos function is:

float acos ( float $arg )

Parameters

The acos function takes a single parameter:

• arg: The value for which to calculate the arc cosine. It must be a number between -1 and 1.

Return Value

The acos function returns the arc cosine of the specified value in radians. If the argument is outside the range of -1 to 1, the function will return NAN (Not a Number).

Examples

Here are a few examples to illustrate the usage of the acos function:

Example 1:

$x = 0.5;
$angle = acos($x);
echo "The arc cosine of $x is: " . $angle;

Output:

The arc cosine of 0.5 is: 1.0471975511966

Example 2:

$x = -0.8;
$angle = acos($x);
echo "The arc cosine of $x is: " . $angle;

Output:

The arc cosine of -0.8 is: 2.4980915447965

Example 3:

$x = 2;
$angle = acos($x);
echo "The arc cosine of $x is: " . $angle;

Output:

The arc cosine of 2 is: NAN

Summary

The acos function in PHP is used to calculate the arc cosine of a number. It returns the angle in radians whose cosine is equal to the specified value. It takes a single argument, which must be a number between -1 and 1. If the argument is outside this range, the function will return NAN. This function can be useful in various mathematical calculations and applications.

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