Inverse cosine

32 · John Cook · March 12, 2026, 5:05 p.m.
Summary
This post explores the mathematical identities involving inverse trigonometric functions, specifically focusing on why sin(arccos(x)) simplifies nicely while sinh(arccosh(x)) does not. It includes a sketch of a proof for these identities, providing an insightful look into the nuances of mathematical simplification.