(PHP 4, PHP 5, PHP 7)
acos — 锟斤拷锟斤拷锟斤拷
$arg
) : float
锟斤拷锟斤拷 arg 锟侥凤拷锟斤拷锟斤拷值锟斤拷锟斤拷位锟角伙拷锟饺★拷acos()
锟斤拷 cos() 锟侥凤拷锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷思锟斤拷锟斤拷
acos() 锟斤拷围锟斤拷锟矫匡拷锟街碉拷锟斤拷锟�
a==cos(acos(a)) 锟斤拷
arg要锟斤拷锟斤拷牟锟斤拷锟�
arg 锟侥凤拷锟斤拷锟揭伙拷锟饺★拷