0_0_13571298_21543.cpp: In function 'int main()': 0_0_13571298_21543.cpp:18:29: error: 'x3' was not declared in this scope scanf("%lf%lf",&x3,&y3); ^ 0_0_13571298_21543.cpp:18:33: error: 'y3' was not declared in this scope scanf("%lf%lf",&x3,&y3); ^