Approximate the cosine function using a function

#include<stdio.h>
#include<math.h>
double funcos(double e,double x)
{
	double a=1,i,k=-1,b=1,c=1,s=1;
	for(i=2;a>e;i+=2)
	{
		b=b*x*x;
		c=c*i*(i-1);
		s=s+k*b/c;
		a=b/c;
		k=-k;
	}

        
	

	return s;
}
intmain()
{
	double a,b,i,k,m;
	double d,s,e,c;
	scanf("%lf%lf",&a,&b);
	printf("sum=%.6lf",funcos(a,b));
	return 0;
}