# Euler's paper for the theorem $e^{i\theta} = \cos(\theta) + i\sin(\theta)$?

Which is Leonard Euler's Paper where he proves this central result? The term 'complex number' does not seem to have been used by him. I'm hoping someone could link me to some page in the Euler archive.

This appears at the end of $\S\,138$ in Introductio (1748). In Blanton's translation this appears on page 112, line 5.