Werner Formula for Cosine by Cosine/Also presented as

Werner Formula for Cosine by Cosine: Also presented as

The Werner Formula for Cosine by Cosine can also be seen in the form:

$2 \cos \alpha \cos \beta = \map \cos {\alpha - \beta} + \map \cos {\alpha + \beta}$

Sources

• 1969: J.C. Anderson, D.M. Hum, B.G. Neal and J.H. Whitelaw: Data and Formulae for Engineering Students (2nd ed.) ... (previous) ... (next): $4.$ Mathematics: $4.3$ Trigonometric identities and hyperbolic functions

• Weisstein, Eric W. "Werner Formulas." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/WernerFormulas.html