Find the norm of \(\mathbf v=(3,4)\).

Find the distance between \(P=(1,-2,3)\) and \(Q=(4,2,-1)\).

Let \(\mathbf v=(2,-1,2)\). Find a unit vector in the same direction as \(\mathbf v\).

Find all real \(t\) such that \(\|(t,2)\|=5\).