Hard Practice — Advanced Set

Quick Recap — Vectors (Hard)

Chain the tools: components for dot/cross, Lagrange's identity, the scalar triple product (volume/coplanarity), and the $|\vec a+\vec b+\vec c|^2$ expansion for problems where $\vec a+\vec b+\vec c=\vec0$. Many are numerical-value (Section B), with cross-topic links to 3D geometry.