math library problem

[Jim Lemon]

Dumb question

On two separate Redhat Linux v5.2 systems, whenever I invoke a trig
function (with #include <math.h>, of course), and try to compile with
gcc v2.7.2.3, I get the error message:

	undefined reference to '...'

where ... is the name of the trig function.  I know this means that the
relevant library is not there, but why only for trig functions?

Thanks

Jim