What is the dot product of $<3,4,1 >$ and $<5,-1,2 >$ ?

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Answer 1 · 2015-12-19T11:26:39

13

$(3hati+4hatj+hatk) * (5hati-hatj+2hatk)$

$= (3hati)*(5hati) + (3hati)*(-hatj) + (3hati)*(2hatk)$

$color(white)(s) + (4hatj)*(5hati) + (4hatj)*(-hatj) + (4hatj)*(2hatk)$

$color(white)(s) + (hatk)*(5hati) + (hatk)*(-hatj) + (hatk)*(2hatk)$

$= 15 + 0 + 0$

$color(white)(s) + 0 - 4 + 0$

$color(white)(s) + 0 + 0 + 2$

$= 13$

What is the dot product of <3,4,1 ><3,4,1 > and <5,-1,2 ><5,-1,2 >?