>> ff1='50*z*(z-d)=230.1875*(z^2-r^2)';
>> ff2='((z-d)*r)^2=29318.942*(z^2-r^2)';
>> ff3='50*(z-d)*r=22.0345*(z^2-r^2)';
>> solve(ff1,ff2,ff3)
??? Error using ==> subsref
Index exceeds matrix dimensions.
Error in ==> sym.subsref at 16
y = builtin('subsref',struct(x),a);
Error in ==> solve at 191
S.(char(symvars(j))) = R(:,j);