[SOLVED] Ortogonal matrix 1. The problem statement, all variables and given/known data I have a 2x2 matrix A: [alfa beta] [beta -alfa], where alfa and beta are real parameters. I have to find out for which values of alfa and beta A is an orthogonal matrix. 3. The attempt at a solution A matrix is orthogonal if it satisfies Q*Q^T = I. So I will multiply A with A^T and equal it to I, and I get the condition alfa^2 + beta^2 = 1. Are there any other conditions I need?