W3School TIY Editor
W3School 在线教程
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暗黑模式
<!DOCTYPE html> <html> <body> <?php echo(acos(0.64) . "<br>"); echo(acos(-0.4) . "<br>"); echo(acos(0) . "<br>"); echo(acos(-1) . "<br>"); echo(acos(1) . "<br>"); echo(acos(2)); ?> </body> </html>