What is the angle between #<-7,2,-3 > # and #< 1,-5,1 >#?

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Answer 1 · 2018-02-26T12:13:23

The angle between #vecA and vecB# is #119.26^0#

#vecA =<-7,2, -3> and vecB =<1,-5,1> ; theta# be the

angle between them ; then we know

#cos theta= (vecA*vecB)/(||vecA||*||vecB||)#

#=((-7.1)+(2* -5)+(-3*1))/(sqrt((-7)^2+2^2+(-3)^2)* (sqrt(1^2+(-5)^2+1^2))#

#= -20/(sqrt62*sqrt27)=-20/40.915 ~~ -0.489#

#:. theta=cos^-1(-0.489)~~119.26^0#

The angle between #vecA and vecB# is #119.26^0# [Ans]