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## Trigonometric Identities Problems

Trigonometric identities are equations that are true for any angle used. These identities are used to rewrite and simplify complex trigonometric expressions. Furthermore, we can also use trigonometric identities to solve trigonometric expressions by rewriting them as...

## Coterminal Angles – Formulas and Examples

Coterminal angles are angles that have the same initial side and the same terminal side. The coterminal angles are equivalent to each other since they represent the same direction. It is possible to have both positive and negative coterminal angles. Here, we will...

## Sum and Difference Identities – Formulas and Examples

The sum and difference identities of angles are trigonometric identities used to calculate the values of certain angles. These identities can be used to rewrite the angles as a sum or subtraction of common angles. For example, to calculate the sine or cosine of 15°,...

## Half-angle identities – Formulas, proof and examples

Half-angle identities are trigonometric identities used to simplify trigonometric expressions and calculate the sine, cosine, or tangent of half-angles when we know the values of a given angle. These identities are obtained by using the double angle identities and...

## Double Angle Identities – Formulas, Proof and Examples

Double angle identities are trigonometric identities used to rewrite trigonometric functions, such as sine, cosine, and tangent, that have a double angle, such as 2θ. These identities are derived using the angle sum identities. We have a total of three double angle...