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9
9
Part of
2021 Stanford Mathematics Tournament
Problems
(1)
SMT 2021 Geometry #9
Source:
8/9/2023
Rectangle
A
B
C
D
ABCD
A
BC
D
has an area of 30. Four circles of radius
r
1
=
2
r_1 = 2
r
1
=
2
,
r
2
=
3
r_2 = 3
r
2
=
3
,
r
3
=
5
r_3 = 5
r
3
=
5
, and
r
4
=
4
r_4 = 4
r
4
=
4
are centered on the four vertices
A
A
A
,
B
B
B
,
C
C
C
, and
D
D
D
respectively. Two pairs of external tangents are drawn for the circles at A and
C
C
C
and for the circles at
B
B
B
and
D
D
D
. These four tangents intersect to form a quadrilateral
W
X
Y
Z
W XY Z
W
X
Y
Z
where
W
X
‾
\overline{W X}
W
X
and
Y
Z
‾
\overline{Y Z}
Y
Z
lie on the tangents through the circles on
A
A
A
and
C
C
C
. If
W
X
‾
+
Y
Z
‾
=
20
\overline{W X} + \overline{Y Z} = 20
W
X
+
Y
Z
=
20
, find the area of quadrilateral
W
X
Y
Z
W XY Z
W
X
Y
Z
. https://cdn.artofproblemsolving.com/attachments/5/a/cb3b3457f588a15ffb4c875b1646ef2aec8d11.png
geometry