Obtained by solving the second and third versions of the cosine double-angle formula.
and in general terms of powers of sin θ or cos θ the following is true, and can be deduced using De Moivre's formula, Euler's formula and the binomial theorem
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These are also known as the addition and subtraction theorems or formulae . The identities can be derived by combining right triangles ...
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In trigonometry, the basic relationship between the sine and the cosine is known as the Pythagorean identity: {\displaystyle \sin ^{2}\...
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By examining the unit circle, the following properties of the trigonometric functions can be established. Symmetry When the trigon...
Labels
- and periodicity
- Angle sum and difference identities
- Angles
- Calculus
- Certain linear fractional transformations
- Composition of trigonometric functions
- Exponential definitions
- Historical shorthands
- Identities without variables
- Infinite product formulae
- Inverse functions
- Inverse trigonometric functions
- Lagrange's trigonometric identities
- Linear combinations
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- Miscellaneous
- MMO
- Multiple-angle formulae
- Other sums of trigonometric functions
- Power-reduction formula
- Product-to-sum and sum-to-product identities
- Pythagorean identity
- Relation to the complex exponential function
- shifts
- Symmetry
- Trigonometric functions