<PRE><B>Question 980796</B>
From your cosine rule,recall that
   CosB=(c²+a²-b²)/2ac
Draw the vector and apply the formula.
 from your diagramme,(i.e triangle) formed by the two vectors,
if a=52,
   b=100
   C=131
   B=?
then,
cosB=(131²+52²-100²)/2*131*52  
evaluating the above,
  cosB=(9865)/(13624)
  cosB=0.7241
  B=cos-1(0.7241)
  B=43.6068degres
now convert 43.6068º to radian
  B=(pi/180)*46.6068
  B=0.7612radian
the angle between them is 0.7612rad
HOPE THIS HELPS? </PRE>