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1300
External Angle Bisector
Editorial
geometry
triangles
angle bisectors
In triangle
A
B
C
ABC
A
B
C
,
A
B
=
5
AB = 5
A
B
=
5
,
A
C
=
10
AC = 10
A
C
=
10
, and
B
C
=
12
BC = 12
B
C
=
12
. The external angle bisector of
∠
A
\angle A
∠
A
meets
B
C
BC
B
C
extended past
B
B
B
at a point
D
D
D
. Find the length of
C
D
CD
C
D
.
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