How do I add a loops output to an existing array as a new row?

I have to write a for loop that loops through the columns of an array A and finds the distance of each column from the origin (where the entry in the first row is the x coordinate, the 2nd row is the y coordinate, and the third row is the z coordinate). I have that loop written. But I need to add the solutions of the loop to the Array A as a 4th row and I can't figure it out. Here's what I have so far:

B=[]; n=1:20;
for col=1: length(A(3,n))
    dist=sqrt((A(1,n)).^2+(A(2,n)).^2+(A(3,n)).^2);
    B=[A, dist];
end

[Elias Beaini]

never mind I got it