a quaternion version of Euler's formula
26:07
Deriving Euler's formula four ways!
30:31
Climbing past the complex numbers.
12:25
Los fantásticos Cuaterniones - Numberphile
11:35
How quaternions produce 3D rotation
19:06
The Trig Hiding Inside the Factorials (And Harmonic Numbers)
23:03
the parabolic trig functions
29:57
Euler's Formula Beyond Complex Numbers
22:51