Question

Have a question about the angle related to cross product and dot product as it relates to to the unknown angle between two vectors.

Answer 1

When a question asks you to find "the minimum angle between" two vectors, is it ok to use the dot product definition? Or do you have to use cross product to find the "minimum' angle?

Answer 2

dot product is ok.

they are just saying they want angle x in

Answer 3

The question literally says Given vectors A and B determine the minimum angle between A and B

Answer 4

0

Answer 5

or \(- \infty\)

Answer 6

So i did it with the dot product and got the larger of the two angles, and AI was wondering if I had to use the cross product to ensure I get the smaller of the two? It has been about two years since I have done any three dimension vector operations and my mind is fuzzy when it comes to the topic

Answer 7

post or link the question,

Answer 8

So the question gives specific values for A and B I am just asking about the concept

Answer 9

Ok substitute A =-3i + j -2K, an B = 2i - 5j + k into the above question and that is what it says verbatim

Answer 10

But I am not looking for help with this specific question, I am trying to find out the concept in general, because my textbook says that to find the "minimum" angle you use cross product. That seemed sketchy to me so I wanted to inquire about the concept

Answer 11

these are 2 planes, and they are defined by their normals. the angles between those normals are fixed. you can cross them or dot them or whatever, just remember the right hand rule.

Answer 12

I think the are saying


if you use dot product and get an angle bigger than 90º, do 180-x to find the "minimum angle"