[Anjuta-list] Error: undefined reference to cos even after including math.h in the C Program

[Jnanesh <jnanesh vsnl net>]

	I am using GNU Compliler gcc 3.2 on Red Hat Linux. When I build the C
program given below after compiling

	/* Created by Anjuta version 1.0.1 */
	/*	This file will not be overwritten */
	#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 the error as 
	main.c:9: undefined reference to sin

Please help to overcome this problem