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ITAMO
2016 ITAMO
1
1
Part of
2016 ITAMO
Problems
(1)
Projection of vertex onto bisectors
Source: ITAMO 2016, Problem 1
5/11/2016
Let
A
B
C
ABC
A
BC
be a triangle, and let
D
D
D
and
E
E
E
be the orthogonal projections of
A
A
A
onto the internal bisectors from
B
B
B
and
C
C
C
. Prove that
D
E
DE
D
E
is parallel to
B
C
BC
BC
.
geometry
angle bisector
projection