Consider two vectors vec(a) , vec(b) whose components are not known. |vec(a)|=3, |vec(b)|=2 and an angle between them is 120^(circ). Without assuming any particular components, calculate the magnitude of the vector product |(vec(a) −3vec(b) ) xx (2vec(a) +vec(b))|.

Jonas Huff

Jonas Huff

Answered question

2022-11-04

Consider two vectors a , b whose components are not known. | a | = 3, | b | = 2 and an angle between them is 120 . Without assuming any particular components, calculate the magnitude of the vector product | ( a 3 b ) × ( 2 a + b ) |
I understand that when I just want to find the vector product given the above information I would use:
| a × b | = | a | | b | sin ( θ ) .
When I do this I end up with | a × b | = 3 3 . I am not sure whether I am supposed to do this and if I am where I go on from here to calculate | ( a 3 b ) × ( 2 a + b ) |

Answer & Explanation

Arely Davila

Arely Davila

Beginner2022-11-05Added 17 answers

Note that for cross-product, we have ( b × a ) = ( a × b )
( a 3 b ) × ( 2 a + b ) = ( a × 2 a ) + ( a × b ) + ( 3 b × 2 a ) + ( 3 b × b ) = ( a × b ) + ( 6 ) ( b × a ) = ( a × b ) + ( 6 ) ( ( a × b ) ) = 7 ( a × b )
I hope this help

Do you have a similar question?

Recalculate according to your conditions!

Ask your question.
Get an expert answer.

Let our experts help you. Answer in as fast as 15 minutes.

Didn't find what you were looking for?