let p, q, r be Point of (TOP-REAL 3); ( p <X> q = 0. (TOP-REAL 3) & r = |[1,1,1]| implies p,q,r are_LinDep )
assume that
A1:
p <X> q = 0. (TOP-REAL 3)
and
A2:
r = |[1,1,1]|
; p,q,r are_LinDep
|[(((p `2) * (q `3)) - ((p `3) * (q `2))),(((p `3) * (q `1)) - ((p `1) * (q `3))),(((p `1) * (q `2)) - ((p `2) * (q `1)))]| = |[0,0,0]|
by A1, EUCLID_5:def 4, EUCLID_5:4;
then
( ((p `2) * (q `3)) - ((p `3) * (q `2)) = |[0,0,0]| `1 & ((p `3) * (q `1)) - ((p `1) * (q `3)) = |[0,0,0]| `2 & ((p `1) * (q `2)) - ((p `2) * (q `1)) = |[0,0,0]| `3 )
by EUCLID_5:14;
then A3:
( ((p `2) * (q `3)) - ((p `3) * (q `2)) = 0 & ((p `3) * (q `1)) - ((p `1) * (q `3)) = 0 & ((p `1) * (q `2)) - ((p `2) * (q `1)) = 0 )
by EUCLID_5:14;
reconsider r = |[1,1,1]| as Element of (TOP-REAL 3) ;
|{p,q,r}| = 0
hence
p,q,r are_LinDep
by A2, Th37; verum