If the median is drawn to BC from A....the length is

sqrt (8^2 - 5^2) = sqrt (64 - 25) = sqrt (39)

If the median is drawn from B to AC......then its length is :

sqrt ( 5^2 + 39/9) + sqrt (5^2 + 39/9)/2 =

(3/2)sqrt ( 264)/3 =

sqrt (264)/2 =

2sqt (66) / 2 =

sqrt (66)