Eroare de compilare: user.cpp: In function ‘bool cmp(cerc, cerc)’: user.cpp:17:73: error: ‘fabs’ was not declared in this scope return a.y / a.x - b.y / b.x < -0.001 or (fabs(a.y / a.x - b.y / b.x) <= 0.001 and a.r > b.r); ^ user.cpp: In function ‘double dist(double, double, double)’: user.cpp:22:26: error: ‘fabs’ was not declared in this scope return fabs(y - m * x) / sqrt(1 + m * m); ^ user.cpp:22:44: error: ‘sqrt’ was not declared in this scope return fabs(y - m * x) / sqrt(1 + m * m); ^