comparing between two array

sorry if my question is trivial , but i'm still beginner and need your help. i have 3 points in the space say a , b, c each one is an array 2x3 , say a=[2 3 4 ; 9 8 7] ,b =[ 5 2 1 ; 6 3 2] , c=[ 4 7 1; 1 2 3]. i want to compare the distance between points a and b (dist12) with the distance between a and c (dist13), which is longer? thank you

[Azzi Abdelmalek]

This is not clear

[Jan]

@mariam: Please post a small example by editing the original question.

[mariam]

@Jan Simon , @Azzi Abdelmalek , i which it is more clear now.