Error: undefined reference to cos

[Jnanesh <jnanesh at vsnl dot net>]

I am using gcc 3.2 on Red Hat Linux 8.0
When I compiled the C program given below using the command: cc test.c

#include <stdio.h>
#include <math.h>
#define pi 3.1415
int main()
{
   double a;
   a=sin(pi/2);
   printf("a = %lf",a);
   return(0);
}

It gives errors as given below

In function `main':
/tmp/ccBFnFNj.o(.text+0x1e): undefined reference to `sin'
collect2: ld returned 1 exit status

Please help me out to see through this problem