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.