Griffiths's Theorem

Griffiths:=proc() local A,B,C,D,P1,P2,m,x1,x2,c1,c2,c3:

D:=Circumcenter(A,B,C):   P1:=[D[1]+x1,D[2]+m*x1]:   P2:=[D[1]+x2,D[2]+m*x2]:

c1:=Ce(Pedal(A,B,C,P1)):   c2:=Ce(Pedal(A,B,C,P2)):   c3:=NinePointCircle(A,B,C):

ConcurrentCes(c1,c2,c3):

end: