# Give an analytical method to find the vector sum of three vectors P, Q and R.

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Give an analytical method to find the vector sum of three vectors P, Q and R.

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Let P, Q and R be represented in component from i.e.,
$\vec P$ = $P_x\hat i+P_y\hat j+P_z\hat k$
$\vec Q$$Q_x\hat i+Q_y\hat j+Q_z\hat k$
$\vec R$$R_x\hat i+R_y\hat j+R_z\hat k$
Let $\vec S$ be their summation vector, i.e.,
$\vec S=\vec P+\vec Q+\vec R$
= $(P_x\hat i+P_y\hat j+P_z\hat k)+(Q_x\hat i+Q_y\hat j+Q_z\hat k)+(R_x\hat i+R_y\hat j+R_z\hat k)$
Addition of vectors obey the commutative as well as associative laws
∴ S = $(P_x+Q_x+R_x)\hat i+(P_y+Q_y+R_y)\hat j+(P_z+Q_z+R_z)\hat k$
Sx = Px + Qx + Rx,
Sy = Pz + Qz + Rz and
Sz = Pz + Qz + Rz.