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National and Regional Contests
Saudi Arabia Contests
Saudi Arabia Pre-TST + Training Tests
2013 Saudi Arabia Pre-TST
1.4
1.4
Part of
2013 Saudi Arabia Pre-TST
Problems
(1)
AB x CC' = AC xBB' if AC'GB' is cyclic
Source: 2013 Saudi Arabia Pre-TST 1.4
9/13/2020
A
B
C
ABC
A
BC
is a triangle,
G
G
G
its centroid and
A
′
,
B
′
,
C
′
A',B',C'
A
′
,
B
′
,
C
′
the midpoints of its sides
B
C
,
C
A
,
A
B
BC,CA,AB
BC
,
C
A
,
A
B
, respectively. Prove that if the quadrilateral
A
C
′
G
B
′
AC'GB'
A
C
′
G
B
′
is cyclic then
A
B
⋅
C
C
′
=
A
C
⋅
B
B
′
AB \cdot CC' = AC \cdot BB'
A
B
⋅
C
C
′
=
A
C
⋅
B
B
′
:
geometry
cyclic quadrilateral
Centroid