The Grad-Shafranov equation is probably the most well-known MHD equation in the field of fusion plasmas. In practice the nature of solution depends on the choice of two functions To(to) and Po(to) and of boundary conditions. Now, consider "SOLOVIEV EQUILIBRIUM" with, yo(r, 2) = Az'(r2 + BR, ) + C(r2 - R. ) where A, B. C are constants and R., stands for the radius of the tokamak machine, respectively. Determine the points of intersection of isocontours with the radial axis (i.e., rt =?)