...我要计算给出顶点的多边形的周长和面积,顶点数目不确定,怎么写...答:double distance(double a , double b , double c , double d) { return 0 ;} double polygonarea(vector <point> & a , int m) { return 0 ;} int main() { double beginX,beginY,lastX,lastY;double dist,sum=0.0;int M;cout<<"请输入顶点数:"<<endl;cin>>M;//point ...