Question: Elliptical Pde solution

Dear sir,

I am using the Maple to solve pde equations but I am not getting analytical solutions for some of the equations. Can you please help me on how to solve one of the pde, like as I have 

(sin(theta)^2*(diff(a(r, theta), r, r))+cos(theta)^2*(diff(a(r, theta), r))/r-sin(2*theta)*(diff(a(r, theta), theta))/r^2+sin(2*theta)*(diff(a(r, theta), theta, r))/r+cos(theta)^2*(diff(a(r, theta), theta, theta))/r^2)*`α__d`^2+cos(theta)^2*(diff(a(r, theta), r, r))+sin(theta)^2*(diff(a(r, theta), r))/r+sin(2*theta)*(diff(a(r, theta), theta))/r^2-sin(2*theta)*(diff(a(r, theta), theta, r))/r+sin(theta)^2*(diff(a(r, theta), theta, theta))/r^2 = 0

this equation is in polar corrdinates, this is analogous to diff(a(x, y), x, x)+`α__d`^2*(diff(a(x, y), y, y)) = 0

in cartesian coordinates