On how sines and cosines of multiplied angles may be expressed by products
Euler presents cosine as an infinite product, which is related to work in E246 and E247. Faber says this is also in the Introductio, pp. 258-283.
Original Source Citation
Opuscula analytica, Volume 1, pp. 353-363.
Opera Omnia Citation
Series 1, Volume 15, pp.509-521.