1508

#include<bits/stdc++.h>

#define INF 1000010000
#define nl '\n'
#define pb push_back
#define ppb pop_back
#define mp make_pair
#define fi first
#define se second
#define pii pair<int,int>
#define pdd pair<double,double>
#define all(c) (c).begin(), (c).end()
#define SORT(c) sort(all(c))
#define rep(i,n) for( int i = 0; i < n; ++i )
#define repi(i,n) for( int i = 1 ; i <= n; ++i )
#define repn(i,n) for( int i = n - 1 ; i >= 0 ; --i )
#define repf(j,i,n) for( int j = i ; j < n ; ++j )
#define die(s) {std::cout << s << nl;}
#define dier(s) {std::cout << s; return 0;}
#define vi vector<int>
typedef long long ll;
#define eps (1.0e-10)
#define MAX_N 50

using namespace std;

typedef complex< double > point, vec;

inline bool eq(const double &a, const double &b){
    return fabs(a - b) < eps;
}

inline double dist(const point &a, const point &b){
    return abs(a - b);
}

inline double cross(const vec &a, const vec &b){
    return (a.real() * b.imag() - a.imag() * b.real());
}
inline point intersection(const point &a1, const point &a2, const point &b1, const point &b2){
    vec b = b2 - b1;
    vec a = a2 - a1;
    return a1 + (cross(b , b1 - a1) / cross(b , a)) * a;
}
inline point rotp(const point& p, double theta){
    return p * exp(point(0 , theta));
}
void DivideCircle(double r, int n, point *v){
    rep(i , n)  v[i] = rotp(point(0 , r) , (i * M_PI) / (n / 2));
}
inline double AreaOfRegularPolygon(double r, int n_even){
    return (n_even / 2) * (r * r * sin( M_PI / (n_even / 2)));
}
inline double AreaOfRoseWindow(double *r, int n, int k){
    if(n/2 == k)    return M_PI*r[k]*r[k] - AreaOfRegularPolygon(r[--k] , n);
    return AreaOfRegularPolygon(r[k] , n) - AreaOfRegularPolygon(r[k - 1] , n);
}
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.precision(0);
    int m;
    cin >> m;
    rep(j , m){
        double r;
        int n,k;
        point p[MAX_N];
        double kr[MAX_N];
        pair<point , point> v0[MAX_N];
        pair<point , point> v1[MAX_N];
        cin >> r >> n >> k;
        DivideCircle(r , n , p);
        rep(i , n / 2){
            v0[i].fi = p[0];
            v0[i].se = p[n / 2 + i];
            v1[i].fi = p[1];
            v1[i].se = p[(n / 2 + i + 1) % n];
        }
        repf(i , 1 , n / 2){
            point q = intersection(v0[i].fi , v0[i].se , v1[i].fi , v1[i].se);
            kr[i] = abs(q);
        }
        kr[0] = 0.;
        kr[n / 2] = r;
        printf("%.4lf\n" , AreaOfRoseWindow(kr , n ,k));
    }
    return 0;
}