Interestingly showing spherical trig identities was how Hamilton demonstrated his quaternions to the royal irish academy when he found them. See (D) through (K)

Interestingly showing spherical trig identities was how Hamilton demonstrated his quaternions to the royal irish academy when he found them. See (D) through (K): https://www.maths.tcd.ie/pub/HistMath/People/Hamilton/Quatern1/ https://www.maths.tcd.ie/pub/HistMath/People/Hamilton/Quater... When i first read this i found it very hard to understand, because i was unfamiliar with spherical trigonometry, but there's quite some beauty to be found there.