MathDB
Problems
Contests
National and Regional Contests
Moldova Contests
Chisinau City MO
1976 Chisinau City MO
132
Chisinau MO p132 1976 X AB/CD = AO x BO / CO x DO in tangential ABCD
Chisinau MO p132 1976 X AB/CD = AO x BO / CO x DO in tangential ABCD
Source:
March 16, 2021
geometry
ratio
tangential
Problem Statement
Let
O
O
O
be the center of a circle inscribed in a convex quadrilateral
A
B
C
D
ABCD
A
BC
D
and
∣
A
B
∣
=
a
|AB|= a
∣
A
B
∣
=
a
,
∣
C
D
∣
=
|CD|=
∣
C
D
∣
=
c. Prove that
a
c
=
A
O
⋅
B
O
C
O
⋅
D
O
.
\frac{a}{c}=\frac{AO\cdot BO}{CO\cdot DO}.
c
a
=
CO
⋅
D
O
A
O
⋅
BO
.
Back to Problems
View on AoPS