Trigonometric Addition Formulas/Also known as

Trigonometric Addition Formulas: Also known as

The trigonometric addition formulas are also known as the trigonometric addition formulae.

They are also known as:

• the addition formulas or addition formulae

• Ptolemy's formulas or Ptolemy's formulae, for Claudius Ptolemy.

• Simpson's formulas or Simpson's formulae, for Thomas Simpson, although this name has been given to various sets of trigonometric identities, which can cause confusion.

Some sources use the term trigonometric addition formulas as a synonym for compound angle formulas.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): addition formulae
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): Ptolemy's formulae
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): addition formulae
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): Ptolemy's formulae
• 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): addition formula
• 2021: Richard Earl and James Nicholson: The Concise Oxford Dictionary of Mathematics (6th ed.) ... (previous) ... (next): addition formulae (in trigonometry)