<p><img alt="1. Legendre Polynomials Prove orthonormality. Start with the differential equations dr dz Multiply the one for P by Pn, the other by Pn. Take the difference and integrate" src="https://media.cheggcdn.com/media%2F9df%2F9df1cc19-b2d3-4ee8-ba9a-a8e73fb98d1e%2FphprYSPYe.png"