#include#includedouble mycos(double x){double y=1,t=1; x*=3.14159265/180; x*=x; for(int i=1;t>1e-6;i+=2) {t*=x/(i*(i+1)); y+=i%4==1?-t:t; } return y;}int main(){double y; y=mycos(30)+mycos(60); //“度”为单位 printf("%.8lf\n",y*y); return 0;}