#include
#include
void main()
{
int n=2;
float x;
double sum=1.0,term=1.0;
printf("input x:");
scanf("%f",&x);
do
{
term=-term*x*x/(n*(n-1));
sum+=term;
n=n+2;
}
while (fabs(term)>=1e-5);
printf("cos(%g)=%.5f\n",x,sum);
}