Integrate an d graph the integral of the product cos mx cos nx (with various integer m and n of your choice) from – a to a as a function of a and conclude orthogonality of cos mx and cos nx (m ≠ n) for a = π from the graph. For what m and n will you get orthogonality for a = π/2, π/3, π/4? Other a, extend the experiment to cos mx sin nx and sin mx sin nx.