MathDB
Problems
Contests
National and Regional Contests
Greece Contests
Greece JBMO TST
2004 Greece JBMO TST
1
1
Part of
2004 Greece JBMO TST
Problems
(1)
angle chasing in convex ABCD with <A=60^o, two symmetric given
Source: Greece JBMO TST 2004 p1
6/18/2019
Let
A
B
C
D
ABCD
A
BC
D
be a convex quadrilateral with
∠
A
=
6
0
o
\angle A=60^o
∠
A
=
6
0
o
. Let
E
E
E
and
Z
Z
Z
be the symmetric points of
A
A
A
wrt
B
C
BC
BC
and
C
D
CD
C
D
respectively. If the points
B
,
D
,
E
B,D,E
B
,
D
,
E
and
Z
Z
Z
are collinear, then calculate the angle
∠
B
C
D
\angle BCD
∠
BC
D
.
geometry
Angle Chasing