Vector Difference: Explained Through Parallelograms

[subhradeep mahata]

Homework Statement

The angle between two vectors a and b (along the adjacent sides of a parallelogram) is an acute angle. The vector a-b will be (a)major diagonal of parallelogram (b)minor diagonal of parallelogram (c)none

Relevant Equations

Vector diagram

We know that the sum of the two vectors is represented by the major diagonal.
Now, if I draw the vector diagram, it turns out to be a diagonal of an entirely different parallelogram. So, my first answer was (c) none.
But, I noticed that when parallelly shifted, it turns out to be the minor diagonal of the above parallelogram. So, I switched to (b).
But the correct answer according to my book is (a).
Can anyone explain this?

 

[Doc Al]

Have you drawn a diagram? Identify vectors a and b and then -b.

 

[subhradeep mahata]

It should look something like this. How should I proceed now?

 

[kuruman]

View attachment 242827
It should look something like this. How should I proceed now?

Complete the parallelogram and draw its diagonals. Then you you will see what's going on.

 

[subhradeep mahata]

I still see it as the minor diagonal of ABEF. Please help me.

 

[Chestermiller]

The answer in your book is wrong. That's why you are so confused.

 

[subhradeep mahata]

Oh, I see.
So what's it going to be?
I am still on (b).

 

[Chestermiller]

Oh, I see.
So what's it going to be?
I am still on (b).

(b) is correct.

 

[subhradeep mahata]

Oh, so that's it.
I guess I have to double check every answer key now.
Thanks.