12.画出下列各曲面所围立体的图形:-|||-(1) z=0 ,z=3, -y=0, -sqrt (3)y=0 ^2+(y)^2=1 (在第一卦限内);-|||-(2) =0, y=0 ,z=0, ^2+(y)^2=({R)^2} ^2+(z)^2=(R)^2 (在第一卦限内).