Linear Algebra
Correlation Is Secretly an Angle
Vectors as arrows and coordinates, the dot product, orthogonality, and a classic correlation puzzle.
What to remember
- Linear combinations au + bv are the core operation of linear algebra.
- u·v = ||u|| ||v|| cos θ measures alignment; zero dot product means orthogonal.
- Correlation is the cosine of the angle between centered variables; use geometry for correlation-bound puzzles.
Read the lessonVectors and Dot Products, with a checkpoint at the end.