% Valid and invalid cases for the first intercept theorem's converse
% Copyright (c) Christian Obrecht 2004

box(-1,-1,13,10)
A = point(0,0)
d1 = line(A,0:)
d2 = line(A,40:)
M = point(d1,8)
B = point(d1,12)
c1 = circle(M,6)
c2 = circle(B,9)
N P intersection(d2,c1)
D C intersection(d2,c2)
MN = segment(M,N)
MP = segment(M,P)
BC = segment(B,C)
BD = segment(B,D)
draw(d1)
draw(d2)
draw(MN)
draw(MP,dashed)
draw(BC)
draw(BD,dashed)
thickness(.5)
draw(c1,angle(MP)-3:,angle(MN)+3:)
draw(c2,angle(BC)-3:,angle(BD)+3:)
draw("A",A,-90:)
draw("B",B,-90:)
draw("C",C,90:)
draw("M",M,-90:)
draw("N",N,135:)
draw("8",barycenter(A,M),-90:)
draw("4",barycenter(M,B),-90:)
draw("6",barycenter(M,N),-145:)
draw("9",barycenter(B,C),0:)