(b) The following problem is to be solved by the method of finite differences in a rectangular grid with Ar = Ay = 1. Draw a sketch of the domain and the grid points. Use symmetry to minimize the number of unknowns, whenever possible. Give the final number of unknown values u; to be solved, and indicate these u; in the sketch, numbering them rowwise as u1, u2, . ... (Note: Do not write down the equations to be solved, and do not solve the equations!) Ouzou =0. 0