Vector problem simple question

[vectordvd]

I am having trouble understanding a question that has a right angle triangle with sides labeled hypotenous=V3, and the other two sides are labeled V1, and V2. The question asks what is V3 equal to, and the correct answer is V2-V1. I can't understand why, I thought it should be the square root of V2^2+V1^2. Can someone please explain this to me?

 

[Gear300]

You're right, but that is a scalar expression. Adding and subtracting with vectors as the elements is interpreted differently than with numbers. Let's say you add 2 vectors. You take the head of one (vec A) and connect it to the tail of the other (vec B). The sum (vec C) is the vector with its tail at the tail of vec A and head at the head of vec B --- A + B = C. Look at the diagram carefully and see how the vectors are connected.

 

[vectordvd]

thank you for helping.