#include<stdio.h>
double getEx(double x,int n){
double temp=1;
for(int i=0;i<n;i++){
temp*=x;
}
return temp;
}
double getJiecheng(int n){
double temp=n;
for(int i=n-1;i>=1;i--){
temp*=i;
}
if(n/2%2==0)
return temp;
else
return -1*temp;
}
double getfabs(double t){
if(t>=0)
return t;
else
return -1*t;
}
void main(){
const double E=1e-6;
double x,t,ans=1;
int n=2;
x=0.5
do{
t=getEx(x,n)/getJiecheng(n);
ans+=t;
n+=2;
if(getfabs(t)<=E){
break;
}
}while(true);
printf("cos(%f)=%f\n",x,ans);
}