AD
= 0.38
DB
AC
= 0.38
CB
C
AD = 5.70 cm
DB = 15.15 cm
AC = 4.27 cm
CB = 11.35 cm
D
A
B
Lemma: An exterior angle bisector partitions the side it
intersects in proportion to the remaining sides.
C
E
D
A
B
A
P
B
C
Lemma: The bisectors of two exterior angles are
concurrent with the bisector of the opposite interior
angle.
E
A
P
F
B
C
D
A
F
B
E
P
D
C
Theorem: The
cevians to the
points of tangency
of the excircles in
any triangle are
concurrent. The
point of
concurrency is
called the Nagel
point.
AF = 3.06 cm
FB = 1.71 cm
BD = 1.81 cm
DC = 3.06 cm
CE = 1.71 cm
EA = 1.81 cm
( )( )( )
AF
BD
CE
·
·
= 1.00
FB
DC
EA
A
excenter
B
C
X
F
W
A
P
E
Y
B
T
D
C V
U