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Problems
Contests
National and Regional Contests
China Contests
China Northern MO
2019 China Northern MO
2
2
Part of
2019 China Northern MO
Problems
(1)
2019 CNMO P2
Source: 2019 China North MO, Problem 2
2/21/2020
Two circles
O
1
O_1
O
1
and
O
2
O_2
O
2
intersect at
A
,
B
A,B
A
,
B
. Diameter
A
C
AC
A
C
of
⊙
O
1
\odot O_1
⊙
O
1
intersects
⊙
O
2
\odot O_2
⊙
O
2
at
E
E
E
, Diameter
A
D
AD
A
D
of
⊙
O
2
\odot O_2
⊙
O
2
intersects
⊙
O
1
\odot O_1
⊙
O
1
at
F
F
F
.
C
F
CF
CF
intersects
O
2
O_2
O
2
at
H
H
H
,
D
E
DE
D
E
intersects
O
1
O_1
O
1
at
G
,
H
G,H
G
,
H
.
G
H
∩
O
1
=
P
GH\cap O_1=P
G
H
∩
O
1
=
P
. Prove that
P
H
=
P
K
PH=PK
P
H
=
P
K
.
geometry