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VMO 1982 — Division A Question 6

VMO · VMO 1982 — Division A

Question 6

Let $ABCD.A'B'C'D'$ be a cube. Prove that no line intersects all four of the following lines: $AA'$, $BC$, $D'C'$, and the line joining the midpoints of the edges $BB'$ and $DD'$.