English Title
Elucidations about the formula, in which the sines and cosines of angles are to be multiplied, where at once large difficulties are diluted
Enestrom Number
686
Fuss Index
148
Original Language
Latin
Content Summary
Euler begins by deriving a polynomial expansion for 2 cos(nφ). He then substitutes z for cos(φ) and s = cos(nφ) and obtains a second order differential equation. He tries to solve that with unknown coefficients and gets another series for cos(nφ).
Published as
Journal article
Published Date
1795
Written Date
1777
Original Source Citation
Nova Acta Academiae Scientiarum Imperialis Petropolitanae, Volume 9, pp. 54-80.
Opera Omnia Citation
Series 1, Volume 16A, pp.282-310.
Record Created
2018-09-25
