MathDB
Problems
Contests
National and Regional Contests
Portugal Contests
Portugal MO
2001 Portugal MO
2
2
Part of
2001 Portugal MO
Problems
(1)
computational in trapezoid, BC = 2 DA, <DAB + <ABC =120^o 2001 Portugal p2
Source:
10/13/2020
The trapezium
[
A
B
C
D
]
[ABCD]
[
A
BC
D
]
has bases
[
A
B
]
[AB]
[
A
B
]
and
[
C
D
]
[CD]
[
C
D
]
(with
[
A
B
]
[AB]
[
A
B
]
being the largest base). Knowing that
B
C
=
2
D
A
BC = 2 DA
BC
=
2
D
A
and that
∠
D
A
B
+
∠
A
B
C
=
12
0
o
\angle DAB + \angle ABC =120^o
∠
D
A
B
+
∠
A
BC
=
12
0
o
, determines the measure of
∠
D
A
B
\angle DAB
∠
D
A
B
.
geometry
trapezoid