def ngon(expr n, x, y, r) = 
save i; path p; 
p:=(x+r*cosd(90),y+r*sind(90)) 
  for i=1 upto n:
    --(x+r*cosd(90+i*(360/n)),y+r*sind(90+i*(360/n))) 
  endfor;
  draw p;
enddef;

def ngons(expr n, x, y, r) = 
save ra; save rb;
  ngon(n,x,y,r);  
  rb:=r/sqrt(n);
  ra:=r-rb;
  for i=1 upto n:
    ngon(n,x+ra*cosd(90+i*(360/n)),y+ra*sind(90+i*(360/n)),rb)
  endfor;
enddef;

def dgons(expr n, k, x, y, r) = 
save ra; save rb;
  ngon(n,x,y,r);  
  rb:=r/sqrt(k);
  ra:=r-rb;
  for i=1 upto n:
    ngon(n,x+ra*cosd(90+i*(360/k)),y+ra*sind(90+i*(360/k)),rb)
  endfor;
enddef;

numeric a,r;

a:=1cm;
r:=5*a;

beginfig(2)

ngon(3,0,0,r);

endfig;

beginfig(3)

ngons(3,0,0,r);

endfig;

beginfig(4)

ngons(4,0,0,r);

endfig;

beginfig(5)

ngons(5,0,0,r);

endfig;

beginfig(6)

ngons(6,0,0,r);

endfig;

beginfig(7)

ngons(7,0,0,r);

endfig;

beginfig(8)

ngons(8,0,0,r);

endfig;

beginfig(9)

ngons(9,0,0,r);

endfig;

beginfig(10)

ngons(10,0,0,r);

endfig;

beginfig(11)

ngons(11,0,0,r);

endfig;

beginfig(12)

ngons(12,0,0,r);

endfig;


beginfig(13)

ngons(13,0,0,r);

endfig;


beginfig(14)

ngons(14,0,0,r);


endfig;

beginfig(15)

ngons(15,0,0,r);

endfig;


beginfig(16)

ngons(16,0,0,r);

endfig;

beginfig(17)

dgons(4,2,0,0,r);

endfig;


beginfig(18)

dgons(6,2,0,0,r);

endfig;

beginfig(19)

dgons(6,3,0,0,r);

endfig;

beginfig(20)

dgons(8,4,0,0,r);

endfig;

beginfig(21)

dgons(8,2,0,0,r);

endfig;

beginfig(22)

dgons(9,3,0,0,r);

endfig;


\end