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International Contests
Tournament Of Towns
1991 Tournament Of Towns
(305) 2
(305) 2
Part of
1991 Tournament Of Towns
Problems
(1)
TOT 305 1991 Autumn A J2 famous 80-80-20 problem with AD =BC
Source:
6/9/2024
In
△
A
B
C
\vartriangle ABC
△
A
BC
,
A
B
=
A
C
AB = AC
A
B
=
A
C
and
∠
B
A
C
=
2
0
o
\angle BAC = 20^o
∠
B
A
C
=
2
0
o
. A point
D
D
D
lies on the side
A
B
AB
A
B
and
A
D
=
B
C
AD = BC
A
D
=
BC
. Find
∠
B
C
D
\angle BCD
∠
BC
D
.(LF. Sharygin, Moscow)
geometry
isosceles
angles