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RotateShape

• To: mathgroup at smc.vnet.net
• Subject: [mg29663] RotateShape
• From: Stephen Weil <stephenweil at yahoo.com>
• Date: Mon, 2 Jul 2001 02:20:24 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

Hi,

I am trying to rotate a regular tetrahedron around an
axis that goes through the center of the tetrahedron
and one of its vertices.  Rotating around the top
vertex is simple it's just RotateShape[tet,0,0,Pi/2]. 


But I haven't been able to rotate about one of the
three other axes.  I tried:

RotateShape[tet,0,Pi-2ArcSin[Cos[Pi/3]/Sin[Pi/3]],Pi/2]

where the x-axis rotation angle is the angle between
the line joining any one vertex to the center and any
other vertex to the center, it's Pi minus the dihedral
angle.  The first z-axis rotation angle should be
either -2Pi/3, 0 or 2Pi/3 depending on which vertex is
being rotated.  But all I get is a wobbly tetrahedron!

Grateful if anyone could assist me.

Regards, Stephen Weil

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