If $A= <-1 ,6 ,-4 >$ and $B= <3, -5, 3 >$ , what is $A*B -||A|| ||B||$ ?

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Answer 1 · 2016-12-14T14:38:26

The answer is $=-92.7$

$vecA=〈-1,6,-4〉$

$vecB=〈3,-5,3〉$

The dot product is $vecA.vecB=〈-1,6,-4〉.〈3,-5,3〉$

$=-3-30-12=-45$

The modulus of $vecA$ is $=∥vecA∥=∥〈-1,6,-4〉∥$

$=sqrt(1+36+16)=sqrt53$

The modulus of $vecB$ is $=∥vecB∥=∥〈3,-5,3〉∥$

$=sqrt(9+25+9)=sqrt43$

Therefore,

$vecA.vecB-∥vecA∥*∥vecB∥=-45-sqrt53*sqrt43$

$=-45-47.7=-92.7$

If A= <-1 ,6 ,-4 >A= <-1 ,6 ,-4 > and B= <3, -5, 3 >B= <3, -5, 3 >, what is A*B -||A|| ||B||A*B -||A|| ||B||?