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Nordic
2019 Nordic
3
Quadrilateral
Quadrilateral
Source: Nordic 2019, P3
April 7, 2019
geometry
quadrilateral
Problem Statement
The quadrilateral
A
B
C
D
ABCD
A
BC
D
satisfies
∠
A
C
D
=
2
∠
C
A
B
,
∠
A
C
B
=
2
∠
C
A
D
\angle ACD = 2\angle CAB, \angle ACB = 2\angle CAD
∠
A
C
D
=
2∠
C
A
B
,
∠
A
CB
=
2∠
C
A
D
and
C
B
=
C
D
.
CB = CD.
CB
=
C
D
.
Show that
∠
C
A
B
=
∠
C
A
D
.
\angle CAB=\angle CAD.
∠
C
A
B
=
∠
C
A
D
.
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