I. Reciprocal Identities
II. Quotient Identities
III. Pythagorean Identities
IV. Cofunction Identities
V. Even/Odd Identities
VI. Sum and Difference Identities
VII. Double Angle Identities
VIII. Half Angle Identities
IX. ProducttoSum Identities
X. SumtoProduct Identities
XI. Other Trig Formulas
