let q1, q2, p be Point of (TOP-REAL 2); ( q1 in LSeg q2,p & q1 <> q2 implies dist q1,p < dist q2,p )
assume that
A1:
q1 in LSeg q2,p
and
A2:
q1 <> q2
; dist q1,p < dist q2,p
(dist q2,q1) + (dist q1,p) = dist q2,p
by A1, Th29;
hence
dist q1,p < dist q2,p
by A2, Th22, XREAL_1:31; verum