.SH DESCRIPTION
The
.BR acos ()
-function calculates the arc cosine of \fIx\fP; that is
-the value whose cosine is \fIx\fP.
+function calculates the arc cosine of
+.IR x ;
+that is
+the value whose cosine is
+.IR x .
.SH RETURN VALUE
On success, these functions return the arc cosine of
.IR x
.BR cos (3),
.BR sin (3),
.BR tan (3)
+.SH COLOPHON
+This page is part of release 3.79 of the Linux
+.I man-pages
+project.
+A description of the project,
+information about reporting bugs,
+and the latest version of this page,
+can be found at
+\%http://www.kernel.org/doc/man\-pages/.