Hyperbolic version of Napier’s mnemonic

I was looking through an old geometry book [1] and saw a hyperbolic analog of Napier’s mnemonic for spherical trigonometry. In hindsight of course there’s a hyperbolic analog: there’s a hyperbolic analog of everything. But I was surprised because I’d never thought of this before. I suppose the spherical version is famous because of its […] The post Hyperbolic version of Napier’s mnemonic first appeared on John D. Cook.