56 lines
1.4 KiB
C++
56 lines
1.4 KiB
C++
#include<cstdio>
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#include<cmath>
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#include<algorithm>
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using namespace std;
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const double eps = 1e-9;
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const double Pi = acos(-1.0);
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double ls[110];
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int n;
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inline double f(double s){
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double ret = 0.0, a, b;
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int i;
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for(i = 0; i < n; ++i)
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{
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a = ls[i];
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b = ls[(i+1) % n];
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ret += acos((a*a+b*b - s*s) / (2.0 * a *b));
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}
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return ret;
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}
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int main(){
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int i, T, temp;
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double as[110], h, s, at[110], ang, l, r, m;
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scanf("%d", &T);
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while(T--){
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scanf("%d%lf%lf", &n, &s, &h);
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for(i = 0; i < n; ++i){
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scanf("%lf", &at[i]);
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at[i] *= Pi / 180.0;
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}
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sort(at, at + n);
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for((temp=0, i = 0); i < n; i+=2){
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as[temp++] = at[i];
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}
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--i;
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i >= n ? i-=2 : 1;
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for(; i >= 0; i-=2)
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as[temp++] = at[i];
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for(i = 0; i < n; ++i)
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ls[i] = 1.0 / tan(as[i]);
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l = 0.0;
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r = 1e20;
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for(i = 0;i < n; ++i){
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ls[i] + ls[(i+1) % n] < r ? r = ls[i] + ls[(i+1)%n] : 1;
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fabs(ls[i]-ls[(i+1)%n]) > l ? l = fabs(ls[i] - ls[(i+1)%n] ):1;
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}
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l += eps;
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r -= eps;
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while(r-l > eps){
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m = (l + r) * 0.5;
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f(m) < 2.0 * Pi ? l = m : r = m;
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}
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printf("%.4lf\n", s/m + h *0.01);
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}
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return 0;
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}
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