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Tournament Of Towns
1984 Tournament Of Towns
(O76) T3
TOT 076 1984 Autumn Train S3 BD + DA = BC in a 100-40-40 triangle
TOT 076 1984 Autumn Train S3 BD + DA = BC in a 100-40-40 triangle
Source:
August 24, 2019
geometry
angles
angle bisector
Problem Statement
In
△
A
B
C
,
∠
A
B
C
=
∠
A
C
B
=
4
0
o
\vartriangle ABC, \angle ABC = \angle ACB = 40^o
△
A
BC
,
∠
A
BC
=
∠
A
CB
=
4
0
o
.
B
D
BD
B
D
bisects
∠
A
B
C
\angle ABC
∠
A
BC
, with
D
D
D
located on
A
C
AC
A
C
. Prove that
B
D
+
D
A
=
B
C
BD + DA = BC
B
D
+
D
A
=
BC
.
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