[" 13.Which the direction cosines of the vector joining the points "A(1,2,-3)" und "],[B(BC-1,-2,1)" ,directed from "A" to "B" ."],[" (A) Show that the vector "{+}+ell" is equally inclined to the axes "OX," OY and "02],[" is Find the position vector of a point "R" which divides the line joining two points "P]