# Trig Identities

These trig identities will come in handy when you are proving complex trigonometry functions. Feel free to print this list of trig identities for revision purposes.

(1)

(2)

(3)

#### Trig Identities – Negative Angles

(1) sine = -sine

(2) cosine = cosine

(3) tangent = - tangent

#### Trig Identities - Supplementary Angles

sine = sine

sine = - sine

sine = - sine

tangent = - tangent

tangent = tangent

tangent = - tangent

cosine = - cosine

cosine = - cosine

cosine = cosine

Learn more about supplementary angles and how it is derived. Note that the results for secant , cosecant and cotangent are essentially the same as the above except that the

#### Trig Identities - Complementary Angles

sine = cosine

sine = cosine

sine = - cosine

sine = - cosine

tangent = cotangent

tangent = - cotangent

tangent = cotangent

tangent = - cotangent

Notice that the trigonometry term changes .Find out more about complementary angles.

These trig identities are useful and should be studied in depth so that you may use them whenever necessary.

Let us look at how to apply these formulas in examples of trignometry identities.