Question.7. A rectangular plate of width a cm with insulated surface has its temperature u equal to zero on both the long sides and one on the short side, so that u(o,y)=0, u(a,y)=0, u(x,00)=0. u(x,o)=kx. Show that the steady state temperature within the plate is (-1)* 2ak u(x, y) = π n=1 n -ny a e sin ηπ.Χ. a