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Re: Pentagon with a sraight edge and compass
Posted:
Sep 2, 1998 3:04 PM
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On 2 Sep 1998, Charlie Mead wrote:
> I would love to have this information. At one timeI knew
> how to do this, but I have forgotten.
Here's what I call the "BISECT-BISECT" construction,
which is one of the simplest. I suppose that you want
to draw your pentagon ABCDE in the circle with center O whose
Northernmost, Southernmost, Easternmost and Westernmost points are NSEW,
with one vertex being at E:
N
| A
B | |
| Y |
| | \ |
| | \|
W--Z--------O---X--------E
| | |
| | |
| | |
C | |
| D
S
What you do is BISECT the segment NO at Y, and then BISECT
the angle OYE; letting the internal bisector YX cut OE in X
and the external one YZ cout OW in Z. Then the perpendiculars
to WE through these points hit the circle in the four other
vertices A,B,C,D as shown.
John Conway
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