define PI 3.1415926 //定义πstruct vect{ double x; double y; double z;};int main(){ vect a,b; double tt,kk,sum; cout<<"please input the coordinate a:"; cin>>a.x>>a.y>>a.z; cout<<"please input the coordinate b:"; cin>>b.x>>b.y>>b.z; tt=a.x*a...