MathDB
Problems
Contests
International Contests
Nordic
2019 Nordic
3
3
Part of
2019 Nordic
Problems
(1)
Quadrilateral
Source: Nordic 2019, P3
4/7/2019
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
.
geometry
quadrilateral