#### Pythagorean Identities are three equations that are commonly used in trigonometry. Most of us know about the concept of the Pythagorean theorem; which is a classic a^{2} + b^{2} = c^{2} ; where a, b, and c are the sides of a right triangle. And do you know that you can write this theorem for trigonometry as well? They are called Pythagorean identities.
The Pythagorean identities are like trigonometric identities or equalities that use trigonometric functions. These identities are as follows:
sin^{2} (Θ) + cos^{2} (Θ) = 1, 1 + tan^{2} (Θ) = sec^{2} (Θ), 1 + cot^{2} (Θ) = csc^{2} (Θ).
The original purpose of these identities is that they can solve complex trigonometric functions with ease. All you have to do is memorize them, and you're good to go.

In these worksheets, your students will work with the Pythagorean Identities. There are 6 worksheets in this set. These are moderately complex problems and a sound understanding of trigonometry is required in order for students to be successful with these worksheets. Students will solve equations by using the Pythagorean Identities. They will also simplify trigonometric expressions. This set of worksheets contains step-by-step solutions to sample problems, both simple and more complex problems, a review, and a quiz. It also includes ample worksheets for students to practice independently. Most worksheets contain between eight and ten problems. When finished with this set of worksheets, students will be able to use the Pythagorean Identities to solve trigonometric equations and to simplify trigonometric expressions. These worksheets explain how to solve problems and simplify expressions using Pythagorean Identities. Sample problems are solved and practice problems are provided.