#include <algorithm>#include <iostream>#include <cstring>#include <cstdio>#include <vector>#include <cmath>using namespace std;const double eps = 1e-8 ;const double PI = acos(-1) ;int sgn(double x) { return (x < -eps) ? -1 : (x > eps) ; }//2D PTstruct PT {double x, y;PT () {}PT (double x, double y) : x(x), y(y) {}void rd() { scanf("%lf %lf", &x, &y) ; }PT operator - (const PT o) { return PT(x - o.x, y - o.y) ; }PT operator + (const PT o) { return PT(x + o.x, y + o.y) ; }PT operator * (double s) { return PT(x * s, y * s) ; }PT operator / (double s) { return PT(x / s, y / s) ; }bool operator < (const PT &o) const { return y < o.y-eps || (y < o.y + eps && x < o.x - eps) ; }bool operator == (const PT &o) const { return !sgn(y - o.y) && !sgn(x - o.x) ; }bool operator != (const PT &o) const { return sgn(y - o.y) || sgn(x - o.x) ; }};double cpr(PT a, PT b) { return a.x * b.y - a.y * b.x ; }double dpr(PT a, PT b) { return a.x * b.x + a.y * b.y ; }double cpr(PT a, PT b, PT c) { return cpr(b - a, c - a) ; }double dpr(PT a, PT b, PT c) { return dpr(b - a, c - a) ; }double vlen(PT a) { return sqrt(a.x * a.x + a.y * a.y) ; }double dist(PT a, PT b) { return vlen(a - b) ; }struct CLE {PT c;double r;CLE () {}CLE (PT c, double r) : c(c), r(r) {}void rd() { c.rd(); scanf("%lf", &r); }PT pt(double kk) { return c + PT(cos(kk), sin(kk)) * r; }double ang(PT a) { return atan2(a.y - c.y, a.x - c.x) ; }double sector0(double k1, double k2){if (k1 > k2 + eps) return sector0(k1, PI) + sector0(-PI, k2);return (k2 - k1) * r * r / 2;}double sector1(double k1, double k2) { return adjust(k2 - k1) * r * r / 2; }double adjust(double kk) {if (kk < -PI) kk += PI * 2;if (kk > PI) kk -= PI * 2;return kk;}bool operator == (const CLE &o) { return c == o.c && !sgn(r - o.r) ; }bool operator != (const CLE &o) { return c != o.c || sgn(r - o.r) ; }};int plside(PT a, PT b, PT c, PT d) { return sgn(cpr(c, a, d) * cpr(c, b, d)); }PT ints(PT a, PT b, PT c, PT d){double v1 = cpr(a, b, c), v2 = cpr(b, a, d);return (c * v2 + d * v1) / (v2 + v1);}double disptoline(PT p, PT a, PT b) { return fabs(cpr(p, a, b)) / dist(a, b); }double disptoseg(PT p, PT a, PT b){PT t = p + PT(a.y - b.y, b.x - a.x) ;if (plside(a, b, p, t) == 1) return min(dist(p, a), dist(p, b));return disptoline(p, a, b);}void ints_line_circle(PT c, double r, PT a, PT b, PT &p1, PT &p2){PT p = c + PT(b.y - a.y, a.x - b.x);p = ints(p, c, a, b);double d = dist(p, c), t = sqrt(r * r - d * d) / dist(a, b);p1 = p + (a - b) * t;p2 = p - (a - b) * t;}double delaunay(PT a, PT b, PT o, double r){int d1 = (dist(a, o) > r - eps);int d2 = (dist(b, o) > r - eps);int dd = (disptoseg(o, a, b) < r - eps);CLE oo = CLE(o, r);double ka = oo.ang(a);double kb = oo.ang(b);if (dd){if (d1 == 0 && d2 == 0) return cpr(o, a, b) / 2;PT p1, p2;ints_line_circle(o, r, a, b, p1, p2);double k1 = oo.ang(p1);double k2 = oo.ang(p2);if (d1 == 1 && d2 == 1){if (dist(p1, a) > dist(p2, a)) swap(p1, p2), swap(k1, k2);double ans = oo.sector1(ka, k1) + oo.sector1(k2, kb);return ans + cpr(o, p1, p2) / 2;}if (disptoseg(p1, a, b) > eps) swap(p1, p2), swap(k1, k2);if (d1 == 1 && d2 == 0) return oo.sector1(ka, k1) + cpr(o, p1, b) / 2;if (d1 == 0 && d2 == 1) return oo.sector1(k1, kb) + cpr(o, a, p1) / 2;}return oo.sector1(ka, kb);}void make_ch_jm_ex(PT p[], PT o[], int n, int &top){top = 0;sort(p, p + n);for (int i = 0, j, k = 1; i < 2 * n - 1; i++){j = (i < n) ? i : 2 * (n - 1) - i;if (i == n) k = top;while (top > k && cpr(o[top - 2], o[top - 1], p[j]) < eps) top--;o[top++] = p[j];}top -- ;}PT pt[10], p0[10];int main(){double x, y;while (~scanf("%lf %lf", &x, &y)){pt[0] = PT(x, y);pt[1].rd();pt[2].rd();PT o;double rr;o.rd();scanf("%lf", &rr);double ans = 0;for (int i = 0; i < 3; i++)ans += delaunay(pt[i], pt[(i+1) % 3], o, rr);printf("%.2fn", fabs(ans));}return 0;}
