Mathematics for IGCSE & O level - Vectors (Section 6 - No. 7)
Which is true if AB = -CD?
AB is in the same direction as CD and half its length.
AB is in the same direction as CD and twice its length.
AB is in the opposite direction as CD and has the same length.
AB is in the opposite direction as CD and has a different length.
Explication
The negative sign indicates opposite direction, the magnitude is the same.