What is the projection of #<8,2,1 ># onto #<9,6,3 >#?

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Answer 1 · 2016-12-21T07:18:55

The answer is #=87/126〈9,6,3〉#

The vector projection of #vecb# onto #veca# is

#=(veca.vecb)/(∥veca∥^2)veca#

The dot product is #veca.vecb=〈8,2,1〉.〈9,6,3〉#

#=(72+12+3)=87#

The modulus of #veca# is #=∥veca∥=∥〈9,6,3〉∥#

#=sqrt(81+36+9)=sqrt126#

The vector projection is #=87/126〈9,6,3〉#