When the vectors are linearly dependent, the vectors given are multiples of each other, and, therefore, have no angle between them such that the their dot products are considered simple products between numbers, rather than A . B = ABcos\Theta, as in the formal definition. Since, if the vectors were linearly independent, they may not exist on the same line, plane, space, and, thus, the existence of an angle between vectors - possibly orthogonal vectors - exists so that their sums are less than or equal to the case in which they are linearly dependent.