Question 131
In the cube $ABCDA'B'C'D'$, let $Q$ be the projection of $D'$ onto $A'C$ and $S$ the projection of $D'$ onto $AC'$. Show that:
a) $A'C \perp (D'QB')$;
b) $QS \parallel (ABC)$.
a) $A'C \perp (D'QB')$;
b) $QS \parallel (ABC)$.
MathNet 2016-part-03 — 184 problems (EN–VI) Question 131
Math Olympiad Vault · MathNet 2016-part-03 — 184 problems (EN–VI)