>>871
#include<stdio.h>
#define USER_PI 3.1415926535897932384626433832795
double user_sin_0_n(int n){
　if(n%4==1) return 1.0;
　if(n%4==3) return -1.0;
　return 0.0;
}
double user_sin(double x){
　double ret=0.0, kaijo=1.0, x_n=1.0;
　int i;
　for(i=1;i<100;i++){
　　kaijo*=i;
　　x_n*=x;
　　ret+=user_sin_0_n(i)*x_n/kaijo;
　}
　return ret;
}
double user_cos(double x){return user_sin(x+USER_PI/2);}
double user_tan(double x){return user_sin(x)/user_cos(x);}
int main(int argc, char *argv[]){
　double x;
　printf("Input x : ");
　scanf("%lf", &x);
　printf("sin(%f)=%f\n", x, user_sin(x));
　printf("cos(%f)=%f\n", x, user_cos(x));
　printf("tan(%f)=%f\n", x, user_tan(x));
　return 0;
}