Thales

Oliver Knill, MathE - 320, Harvard Extension School, Spring 2010-2011

c[{a_,b_}]:=a+I b;arg[{a_,b_}]:=Arg[c[{a,b}]];
Manipulate[Graphics[t1=-Pi/2-Pi/3;t2=-Pi/2+Pi/3;t3=Pi/2-t;
p1={Cos[t1],Sin[t1]};p2={Cos[t2],Sin[t2]};p3={Cos[t3],Sin[t3]};
{{RGBColor[1,1,0],Polygon[{p1,p2,p3,p1}]},{RGBColor[1,0,0],Thickness[0.002],Circle[{0,0},1]},{RGBColor[0,0,1],{Disk[p1,0.1],Disk[p2,0.1],Disk[p3,0.1]}},{RGBColor[0,0,1],Point[{0,0}]},alpha=arg[p1-p3];beta=arg[p2-p3];{RGBColor[1,0.5,0],Disk[p3,0.3,{Min[alpha,beta],Max[alpha,beta]}]},{RGBColor[0,1,0],Thickness[0.004],Line[{p1,p2,p3,p1}]}},PlotRange->{{-1.5,1.5},{-1.5,1.5}},ImageSize->400],{t,0,2Pi}]