Two vectors are equal, or represented by equivalent directed segments, when their components are equal. For nonzero vectors, this is the same as having equal magnitude and the same direction. For vectors and , we write .
a
b
a=b
Equivalent vectors can have different positions in a plane or space, but they maintain the same magnitude and direction.
Example of Equivalent Vectors
The purple and orange vectors have the same magnitude and direction, making them equivalent despite their different positions.
Two vectors are equal only when both conditions hold at the same time, so check both before you call them equal. A pair that satisfies only one of the two conditions is not equivalent.
Two vectors are equivalent when they share the same length and the same direction, so either one can stand in for the other. That replacement moves a vector to a convenient starting point without changing the vector itself.
Vector equality follows from equality of every component. Reflexivity compares a vector with itself, symmetry swaps the order of two equal vectors, and transitivity connects two equalities through a shared intermediate vector.
Two vectors are equivalent when the change in the first coordinate matches and the change in the second coordinate matches. The examples below compare those changes directly.
Equivalent vectors have the same magnitude and direction even when their starting points differ. The same displacement can therefore be drawn at different positions without changing the vector. This is useful when comparing translations or moving a vector within a geometric construction.