MathDB
Problems
Contests
National and Regional Contests
India Contests
India Pre-Regional Mathematical Olympiad
2015 India PRMO
16
16
Part of
2015 India PRMO
Problems
(1)
PRMO 2015. p16.
Source:
4/9/2024
16.
16.
16.
In an acute angle triangle
A
B
C
,
ABC,
A
BC
,
let
D
D
D
be the foot of the altitude from
A
,
A,
A
,
and
E
E
E
be the midpoint of
B
C
.
BC.
BC
.
Let
F
F
F
be the midpoint of
A
C
.
AC.
A
C
.
Suppose
∠
B
A
E
=
4
0
o
.
\angle{BAE}=40^o.
∠
B
A
E
=
4
0
o
.
If
∠
D
A
E
=
∠
D
F
E
,
\angle{DAE}=\angle{DFE},
∠
D
A
E
=
∠
D
FE
,
What is the magnitude of
∠
A
D
F
\angle{ADF}
∠
A
D
F
in degrees
?
?
?
Angle Chasing
geometry
Concyclic