:: deftheorem defines lie_on_a_triangle ANPROJ_2:def 2 :
for V being RealLinearSpace
for u, v, w, u1, v1, w1 being Element of V holds
( u,v,w,u1,v1,w1 lie_on_a_triangle iff ( u,v,w1 are_LinDep & u,w,v1 are_LinDep & v,w,u1 are_LinDep ) );