题解 | 三角形面积

double getArea(triangle T) {
    double a = sqrt((T.a.x - T.b.x) * (T.a.x - T.b.x) + (T.a.y - T.b.y) *
                    (T.a.y - T.b.y));
    double b = sqrt((T.a.x - T.c.x) * (T.a.x - T.c.x) + (T.a.y - T.c.y) *
                    (T.a.y - T.c.y));
    double c = sqrt((T.c.x - T.b.x) * (T.c.x - T.b.x) + (T.c.y - T.b.y) *
                    (T.c.y - T.b.y));
    double s=(a+b+c)/2;
    return sqrt(s*(s-a)*(s-b)*(s-c));
}