Hyperbolic version of Napier’s mnemonic

· John Cook · April 3, 2026, 2:03 a.m.
Math memory Geometry mathematics Geometry trigonometry education
Summary
The blog post by John D. Cook discusses discovering a hyperbolic analog of Napier’s mnemonic for spherical trigonometry while reviewing an old geometry book. The author expresses surprise and curiosity about this analog, reflecting on its relationship to the spherical version that is more widely recognized.
Read full post on www.johndcook.com →
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