C语言求sinx

#include int main() { double x,sum=0,pre=0; int n,i=1; scanf("%lf %d",&x,&n); pre=x; for(i=1; i<=2*n-1; i+=2) { sum+=pre; pre=-pre*x*x/((i+1)*(i+2)); } printf("%.8f",sum); return 0; }