Consider the two vectors in $R^3$

vec$(u)=(-4,-20,-12)$ and vec$(v)=(4,c,12)$

Where $c$ is an unknownt.

$($a$)$ For what valuc of $c$ are $si$ and vec$(v)$ colinear?

Answer: $c=$

$($b$)$ For what value of $c$ are $u^{}$ and vec$(v)$ orthogonal?

Answer $c=$

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