If A = i + j + k and B = -I + -j + -k, then (A-B) will make angle with A?

Jul 2018
22
1
If A = i + j + k and B = -i + -j + -k , then (A-B) will make angle with A? What is the concept behind it, could you please explain with a diagram? (this is the part from scalar and vector)
 
Apr 2015
1,035
223
Somerset, England
I think it's your turn to have a go, right or wrong, before we help you.

Note you learn more from getting it wrong than getting it right.

If you did this in your opening post you would save lots of time and effort.

Hint. Think about what sort of object A, B and (A-B) are.
 
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topsquark

Forum Staff
Apr 2008
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On the dance floor, baby!
If A = i + j + k and B = -i + -j + -k , then (A-B) will make angle with A? What is the concept behind it, could you please explain with a diagram? (this is the part from scalar and vector)
A hint: How do you find the angle between any two vectors?

-Dan
 
Jul 2018
22
1
I think it's your turn to have a go, right or wrong, before we help you.

Note you learn more from getting it wrong than getting it right.

If you did this in your opening post you would save lots of time and effort.

Hint. Think about what sort of object A, B and (A-B) are.
Would it be unit vectors?
 
Aug 2010
434
174
Good. Notice that, since B= -A, A- B= A- (-A)= 2A. So what is the angle between A and 2A?
 
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Apr 2015
1,035
223
Somerset, England
Good. Notice that, since B= -A, A- B= A- (-A)= 2A. So what is the angle between A and 2A?
Indranil
Note that 2 is a scalar. What happens to direction when you multiply (scalar * vector) ?

Note that you asked for diagrams.
I started to think about drawing htese like the last lot but you demonstrated some ability with algebra.

The foregoing discussion shows how much easier algebra is in this 3 dimensional case.

Do you still want diagrams ar can you now draw your own?

One thing you suggested when I asked what A, B and (A-B) are was that they are unit vectors.

Do you still think this or can you see why none of them are unit vectors?
 
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