Question

If the position vector of a point (−4, −3) be \[\vec{a,}\] find \[\left| \vec{a} \right|\]

Answer 1

Given a point \[\left( - 4, - 3 \right)\]  such that its position vector \[\vec{a}\]  is given by \[\vec{a} = - 4\hat{i}- 3 \hat{j}\] 
Then,
\[\left| \vec{a} \right| = \sqrt{\left( - 4 \right)^2 + \left( - 3 \right)^2} = \sqrt{16 + 9} = \sqrt{25} = 5\]