In a triangle ABC which of the following is not true-

\(\vec{AB}\) +\(\vec{BC}\)-\(\vec{CA}\) =\(\vec{0}\)

by the triangle law of addition in the given triangle, we have

\(\vec{AB}\)+\(\vec{BC}\)  =\(\vec{AC}\).................(i)

⇒\(\vec{AB}\)+\(\vec{BC}\)  = -\(\vec{CA}\)

⇒\(\vec{AB}\) +\(\vec{BC}\)+\(\vec{CA}\) =\(\vec{0}\)...........(ii)

Hence option A is true.

Similarly we can prove \(\vec{AB}\) +\(\vec{BC}\)- \(\vec{AC}\)  =0 ̅  and \(\vec{AB}\) -\(\vec{CB}\)+\(\vec{CA}\) =0 ̅ are true so  that option B And option D are  also correct.

Finally, the  false option is C.