question_answer

Show that \[A={{\left( \overset{\to }{\mathop{A}}\,.\overset{\to }{\mathop{A}}\, \right)}^{1/2}}\]                                

Answer:

As \[\overset{\to }{\mathop{A}}\,.\overset{\to }{\mathop{A}}\,=A.A\cos {{0}^{o}}={{A}^{2}}\]or \[A={{\left( \overset{\to }{\mathop{A}}\,.\overset{\to }{\mathop{A}}\, \right)}^{1/2}}\]