If the vectors 
and 
are the sides of a triangle ABC, then the length of the median through A is:
(1) 
(2) 
(3) 
(4) 
[JEE Main 2013]
Solution
Let observer be placed at A, then
= position vector of B & 
= position vector of C
Since D is the mid-point of BC,
position vector of D = 
(position vector of B + position vector of C)
Hence, (3).