11.The position vectors of the vertices A, B, C of a triangle ABC are respectively . Find the vectors determined by the sides and calculate the length of the sides.

12.Show that the points whose position vectors given by    are collinear.

Hence, A, B, C are collinear.

13.Find a unit vector in the direction of 

14.Find the unit vectors parallel to the sum of

15.Find the unit vector parallel to   where .

16.The vertices of a triangle have position vectors . Prove that the triangle is equilateral.

17.Show that the vectors form a right angled triangle.

18.If the position vectors of P and Q are    and  , find and determine its direction cosines.