f(x,y)=【2x/(x2+y2+1)，2y/(x2+y2+1)，( x2+y2+1)/(x2+y2-1)】
Select a circle C orthogonal to the unit circle in the xy plane. Construct the surface formed by the line segments connecting points on C to the corresponding stereographic images.
作法
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Construct the spiral as thus: |
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The stereographic projection from the xy plane to the unit
sphere is given by
f(x,y)=【2x/(x2+y2+1)，2y/(x2+y2+1)，( x2+y2+1)/(x2+y2-1)】 Select a circle C orthogonal to the unit circle in the xy plane. Construct the surface formed by the line segments connecting points on C to the corresponding stereographic images. 作法
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Construct three cylinders with any two touching at one point. |
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Construct one-half of the tangent cone to a sphere. |
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Construct one-half of a right solid cylinder whose boundary consists of the helicoid, part of the cylinder and two semi-disks. |
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Construct the cyclide by inverting a torus. |