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1970 IMO Shortlist
5
M is interor point of ABCD - volume problem
M is interor point of ABCD - volume problem
Source:
September 23, 2010
geometry
3D geometry
tetrahedron
Volume
equation
IMO Shortlist
Problem Statement
Let
M
M
M
be an interior point of the tetrahedron
A
B
C
D
ABCD
A
BC
D
. Prove that
M
A
⟶
vol
(
M
B
C
D
)
+
M
B
⟶
vol
(
M
A
C
D
)
+
M
C
⟶
vol
(
M
A
B
D
)
+
M
D
⟶
vol
(
M
A
B
C
)
=
0
\begin{array}{c}\ \stackrel{\longrightarrow }{MA} \text{vol}(MBCD) +\stackrel{\longrightarrow }{MB} \text{vol}(MACD) +\stackrel{\longrightarrow }{MC} \text{vol}(MABD) + \stackrel{\longrightarrow }{MD} \text{vol}(MABC) = 0 \end{array}
M
A
⟶
vol
(
MBC
D
)
+
MB
⟶
vol
(
M
A
C
D
)
+
MC
⟶
vol
(
M
A
B
D
)
+
M
D
⟶
vol
(
M
A
BC
)
=
0
(
vol
(
P
Q
R
S
)
\text{vol}(PQRS)
vol
(
PQRS
)
denotes the volume of the tetrahedron
P
Q
R
S
PQRS
PQRS
).
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