1. Show that the points with position vectors 2
+3
+
,
+
, 6
+ 11
+5
-are collinear
Sol:
2) If the position vectors of A, B, C, D are respectively 2i + 4k, 5i + 3
j + 4k,-2
j + k, 2i + k then prove that CD is parallel to 
and 
= 
Sol:
3. If the position vectors of the points A, B, C are -2i + j -k, 2j + 2k - 4i,6i -3j -13k and 
= k 
, find k.
Sol: 
4) If ABCDEF is a regular hexagon with centre G, then prove that + + 
+ 
+ 
= 3 = 6 
5. In ΔABC, S is the circumcentre and O is the orthocentre then show that
i)SA + SB + SC = SO ii) OA + OB + OC = 2OS
Sol: Given : Circumcentre S and orthocentre O;
Writer - Sayyad Anwar
