Find the distance between $P_{1}=(1, 3,-2)$ and $P_{2}=(2,-1,-3)$.

Solution $$|P_{1}~P_{2}|=\sqrt{(2-1)^{2}+(-1-3)^{2}+(-3+2)^{2}}= \sqrt{1+16+1}=\sqrt{18}=3\sqrt{2}\qquad$$