Prove that the row vectors of an orthogonal matrix A are unit vectors that are orthogonal to one another. My text gave the following hint: If A and B are nxn matrices satisfying BA=I, then B=A inverse and A=B inverse.

I know that orthogonal matrices have columns that are unit vectors that are orthogonal to one another, but I am unsure how to prove that the rows follow the same properties.

If you have any ideas, I would appreciate it. Thanks!