If \[\overrightarrow{a}\] , \[\overrightarrow{b}\], \[\overrightarrow{c}\]. are mutually perpendicular vectors of equal magnitudes, show that the vector \[\overrightarrow{a}+\overrightarrow{b}+\overrightarrow{c}\] is equally inclined to \[\overrightarrow{a}\] , \[\overrightarrow{b}\]and \[\overrightarrow{c}\].