1. The problem statement, all variables and given/known data Show that if A is orthogonal, then AT is orthogonal. 2. Relevant equations AAT = I 3. The attempt at a solution I would go about this by letting A be an orthogonal matrix with a, b, c, d, e, f, g, h, i , j as its entries (I don't know how to draw that here)...but this would be a 3x3 matrix with entries a, b, c, d, e, f, g,h, i, j. I would then construct AT, and then multiply the two matrices. I should find that the non-diagonal entries are zero, but how would I show that the diagonal entries are 1?