\(\(Plot3D[\((\ 1 - x\^2 - y\^2)\)\^\(1/2\), {x, \(-2\), \ 2}, 
      \ {y, \ \(-2\), \ 2}, \ PlotPoints\  -> 60]


	\)\)

\(Plot3D[
      \((\ \(-x\^2\) - y\^2 + \@\(x\^2 + \(y\^2\)\^\(
	\)\))\)\^\(1/2\), {
        x, \(-2\), \ 2}, \ {y, \ \(-2\), \ 2}, \ PlotPoints\  -> 60]\)

Plot3D [ (Sqrt[-(x^2) - (y^2) + (Sqrt[(x^2) + (y^2)])]), {x, 0,  1}, 
       {y,  0,  1},  PlotPoints  -> 100]

Plot3D [ (Sqrt[-(x^2) - (y^2) + 1]), {x, -1,  1}, 
       {y,  -1,  1},  PlotPoints  -> 50]

Plot3D [ (Sqrt[-(x^2) + (Sqrt[(x^2)]) -  .23]), {x, -1, 1}, 
       {y,  -1, 1},  PlotPoints  -> 50]

Plot3D [ 
      (Sqrt[-(x^2) - (y^2) + (Sqrt[(x^2) + (y^2)]) -  .249]), {x, - .52, 
          .52},  {y,  - .52,   .52},  PlotPoints  -> 200,  
      Mesh -> False,  Boxed -> False]

Plot3D [ 
      (Sqrt[((-(((x))^2))/2) - ((((y))^2)/2) + 
          (Sqrt[(((x))^2) + (((y))^2)]) -  .125]), {x, -2, 2}, 
       {y,  -2,  2},  PlotPoints  -> 50,  Mesh -> False,  
      Boxed -> False]