% Centre de la sphere circonscrite
% 1. Definition des points caracteristiques de la geometrie
\figinit{4cm,ortho}
% Sommets
\figpt 1:$A$(0.5,0.8,1.3)
\figpt 2:$B$(0,0)
\figpt 3:$C$(1,0.5)
\figpt 4:$D$(0,1.4)
\figptcircumcenter 5:$O_A$[2,3,4]\figgetdist\Rcc[2,5]
% Plan de base (11,12,13,14)
\figpt 11:(-0.3,-0.3)\figpt 12:$P$(1.5,-0.3)
\figvectC 0(0,2)\figptstra 13=12,11/1,0/
\figvectC 10(0,0,1)% Vecteur orthogonal au plan de base
%
\figptbary 20:[1,2;1,1]% Milieu de [A,B]
% Centre de la sphere circonscrite : 21
\figvectP 24[2,1]\figptinterlineplane 21 :$O$[5,10; 20,24]
\figptrot 22:=21/20,90,24/
\figvectP 0[21,20]\figptstra 30=20,21,22/0.7,0/
\figvectP 0[22,20]\figptstra 30=30,31,32/0.7,0/
\figptstra 32=32/-0.3,0/
\figvectP 0[30,31]\figptstra 31=31/0.3,0/
\figvectP 0[30,32]\figptstra 33=31/1,0/
%
\figset proj(psi=15,theta=25)
% 2. Creation du fichier graphique
\psbeginfig{}
\figptvisilimSL 34:[ 30,31;1,2]
% Plan mediateur
\psset(color=0.7,fill=yes)\psline[33,32,30,31]
\psset(color=\defaultcolor,fill=no)
\psline[33,32,30,31]\psarccircP 30 ; 0.15 [31,32,32]
% Aretes externes du tetraedre
\psset(dash=4)\psline[20,34]
\psset(dash=\defaultdash)
\psline[2,3,4,2]\psline[34,2]
\psaltitude 0.05[1,20,21]\psline[20,21]
% Axe du cercle et cercle
\figpttra 0:=5/1,10/\psline[0,5]
\figpttra 0:=5/-0.5,10/\psset(dash=4)\psline[0,5]\psset(dash=\defaultdash)
\pscirc 5,2,3(\Rcc)
% Plan de base
\psline[11,12,13,14]
\psarccircP 12 ; 0.3 [13,11,11]
\psendfig
% 3. Inscription du texte sur le dessin
\def\dist{2pt}
\figvisu{\figBoxA}{\it Centre de la sph\`ere circonscrite \rm(p. 129)}{%
\figwriten 1:(\dist)\figwritenw 2:(\dist)
\figwritesw 3:(\dist)\figwritene 4:(\dist)
\figwritee 5,21:(\dist)
\figwritege 12:(10pt,2pt)\figwritegce 30:$Q$(4pt,1pt)
}
\centerline{\box\figBoxA}