What is the projection of $(-9 i + j + 2 k)$ onto $(-5i + 12j- 5 k)$ ?

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Answer 1 · 2017-09-27T06:33:16

Let

$vecA=−9hati+hatj+3hatk$

and

$vecB=−5hati+12hatj-5hatk$

Now projection of $vecA$ onto $vecB$

$=(vecA*vecB)/abs(vecB)^2vecB$

$=(45+12-15)/(sqrt(5^2+12^2+5^2))^2(-5hati+12hatj-5hatk)$

$=21/97(-5hati+12hatj-5hatk)$

What is the projection of (-9 i + j + 2 k) (-9 i + j + 2 k) onto (-5i + 12j- 5 k)(-5i + 12j- 5 k)?