Prove or disprove:

(a) There exists a triangle /, ABC in a plane such that |AB|=1 |BC|=2, and |CA|=2 .
(b) There exists a triangle /, ABC in a plane such that |AB| = 1, |BC|=2, and |CA|=3 .
(c) There exists a triangle /, ABC in a plane such that |AB|=1 , |BC|=2, and |CA|=4 .