What is the projection of <3,1,5><3,1,5> onto <2,3,1><2,3,1>?

1 Answer
Jan 20, 2018

The vector projection is = <2, 3, 1>=<2,3,1>

Explanation:

The vector projection of vecbb onto vecaa is

proj_(veca)vecb=(veca.vecb)/(||veca||)^2vecaprojab=a.b(a)2a

veca=<2,3,1>a=<2,3,1>

vecb= <3, 1,5>b=<3,1,5>

The dot product is

veca.vecb =<3,1,5>. <2,3,1> a.b=<3,1,5>.<2,3,1>

= (3)*(2)+(1) *(3)+(5)*(1)=6+3+5=14 =(3)(2)+(1)(3)+(5)(1)=6+3+5=14

The modulus of vecaa is

=||veca||=||<2,3,1>|| =sqrt((2)^2+(3)^2+(1)^2)=sqrt14=a=||<2,3,1>||=(2)2+(3)2+(1)2=14

Therefore,

proj_(veca)vecb=14/14<2, 3,1>projab=1414<2,3,1>