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National and Regional Contests
Korea Contests
Korea Junior Mathematics Olympiad
1998 Korea Junior Math Olympiad
7
7
Part of
1998 Korea Junior Math Olympiad
Problems
(1)
(1998 KJMO P7) ADE is an isosceles triangle
Source: 1998 KJMO P7
6/30/2024
O
O
O
is a circumcircle of non-isosceles triangle
A
B
C
ABC
A
BC
and the angle bisector of
A
A
A
meets
B
C
BC
BC
at
D
D
D
. If the line perpendicular to
B
C
BC
BC
passing through
D
D
D
meets
A
O
AO
A
O
at
E
E
E
, show that
A
D
E
ADE
A
D
E
is an isosceles triangle.
geometry
circumcircle
angle bisector
KJMO