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IMO 1959–1966 - Longlisted Problems (individual years unknown) Question 17

IMO Shortlist · IMO 1959–1966 - Longlisted Problems (individual years unknown)

Question 17

(ROM) Suppose $ABCD$ and $A^\prime B^\prime C^\prime D^\prime$ are two parallelograms arbitrarily arranged in space, and let points $M,N,P,Q$ divide the segments $AA^\prime,BB^\prime,CC^\prime,DD^\prime$ respectively in equal ratios.

(a) Show that $MNPQ$ is a parallelogram;

(b) Find the locus of $MNPQ$ as $M$ varies along the segment $AA^\prime$.