MathNet 2018-part-05 — 181 problems (EN–VI) Question 22

Let $ABCD$ be a regular tetrahedron, with $AB = a$. Denote $M$ the midpoint of $[BC]$, $N$ the midpoint of $[AM]$, and take $P \in [BD]$ so that $BP = 3PD$. Compute the distance between the straight lines $AC$ and $NP$.

Gabriela Chişiu and Carmen Rusu