1

r(t):=[3*t^2-3,4-7*t,-t^3];

r(0);

r(2);

sqrt(r(0).r(0));

sqrt(r(2).r(2));

2

r1:[-2,1,0];

r2:[5,3,1];

r3:[0,-2,7];

OA:r1;

AC:-r1+r3;

AB:-r1+r2;

load("vect");

express(express(r1~r2)~r3);

express(r1~express(r2~r3));

r1.express(r2~r3);

r2.express(r3~r1);