#include<cstring>
#include<cstdio>
#include<cmath>
using namespace std;

double pi=asin(1.0f);
double GetAng(double R){
    double re,mid,hig = pi,low=0;
    while( hig-low > 10e-8){
        mid = (hig+low)/2.0f;
        re = mid/sin(mid);
        if(re>R)hig=mid;
        else if(re<R)low=mid;
        else break;
    }
    return mid;
}

int main(void){
    double L,n,C,a;
    while(true){
        scanf("%lf %lf %lf",&L,&n,&C);
        if(L<0 || n<0 || C<0)break;
        a = GetAng(1.0f+n*C);
        printf("%.3lf\n", L*( (1.0f-cos(a)) / (2*sin(a))) );
    }
    return 0;
}

• 这题是不是有什么特殊的数据啊？？ (10) ACM29187 2004-10-13 23:19:49
  • Re:这题是不是有什么特殊的数据啊？？ (14) westlife 2004-10-14 03:56:22
• 估计用sin和cos就会出精度问题 (0) ACM29001 2004-10-13 23:40:46
• Re:Help! (43) zskof 2004-10-14 10:02:54