Every trigonometric function's manpage references every other,
with a single exception: sin(3) does not Xr cos 3.
Jan
Index: sin.3
===================================================================
RCS file: /cvs/src/lib/libm/man/sin.3,v
retrieving revision 1.16
diff -u -p -r1.16 sin.3
--- sin.3 17 Jul 2013 05:42:11 -0000 1.16
+++ sin.3 26 Sep 2017 22:18:57 -0000
@@ -72,6 +72,7 @@ functions return the sine value.
.Xr asin 3 ,
.Xr atan 3 ,
.Xr atan2 3 ,
+.Xr cos 3 ,
.Xr cosh 3 ,
.Xr sinh 3 ,
.Xr tan 3 ,
