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$($a$)$ vec$(d{)}_1*vec(d{)}_2$

$($b$)(vec(d{)}_1+$vec$(d{)}_2)*vec(d{)}_2$

$($c$)$ What is the component of vec$(d{)}_1$ along the direction of vec$(d{)}_2.($Hint: Consider the equation and the figure below for this part.$)$

vec$(a)*vec(b)=$abcos$$

$($a$)$

$($b$)$