If #A= <8 ,1 ,-1 ># and #B= <-2 ,4 ,3 >#, what is #A*B -||A|| ||B||#?

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Answer 1 · 2017-01-28T06:36:42

The answer is #=-58.75#

Let 's start by calculating the dot product

#vecA.vecB=<8,1,-1>.<-2,4,3>#

#=-16+4-3=-15#

The modulus of #vecA#

#=||vecA||=||<8,1,-1>||=sqrt(64+1+1)=sqrt66#

The modulus of #vecB#

#=||vecB||=||<-2,4,3>||=sqrt(4+16+9)=sqrt29#

Therefore,

#vecA.vecB-||vecA||*||vecB||#

#=-15-sqrt66*sqrt29=-58.75#