RETURNS the arc cosine of an argument given in radians.
Compatible with LOCALE only, up to PHP 7.4.XX.
<?php
float acos ( float $num )
where,
$num = The argument to process in radians
?>
EXERCISE
<table width="100%" border="1" cellspacing="5" cellpadding="5">
<tr><td colspan="4">acos($num)</td></tr>
<tr><td>DEGREES ( ° )<td>RADIANS ( rd )</td><td>OPERATION</td><td>RESULT</td></tr>
<?php
// setlocale(LC_ALL, 'pt_BR', 'pt-BR');
$pi = M_PI;
$pi_arr01 = [ '0' => 0, 'Л/4' => $pi/4,
'Л/2' => $pi/2, '3Л/4' => 3*$pi/4, 'Л' => $pi, '5Л/4' => 5*$pi/4,
'3Л/2' => 3*$pi/2, '7Л/4' => 7*$pi/4, '2Л' => 2*$pi ];
foreach($pi_arr01 as $val_a => $val_n)
{
echo '<td>' . rad2deg($val_n) . '</td>';
echo '<td>' . $val_a . '</td>';
echo '<td>acos( ' . cos($val_n) . ' )</td>';
echo '<td>' . acos(cos($val_n)) . '<br><br>' . rad2deg(acos(cos($val_n))) . '°' . '</td></tr>';
}
?>
<td colspan="4">ed48</td></tr></table>
EXERCISE
<?php
// setlocale(LC_ALL, 'pt_BR', 'pt-BR');
$num02a = 0.70710678118655;
$num02b = cos(acos($num02a));
$num02c = acos($num02a);
if($num02a == $num02b)
{
echo 'The values of the tested arguments are equal.<br><br>';
echo $num02a . ' = ' . $num02b . ' = ' . rad2deg($num02c) . '°<br>';
}
else
{
echo 'The values of the tested arguments are diferent<br><br>';
echo $num02a . ' ≠ ' . $num02b . '<br>';
}
?>