# Identity

In mathematics, an identity is an equality that holds true for all values of the variables within its domain. It is a relationship between two mathematical expressions that are equal for all possible values of the common variables. For example, in trigonometry, the Pythagorean identity holds for all values of .

An identity typically represents a property of the operations involved, and they are often used to simplify expressions or solve equations.

## Disambiguation

• A Law is a universally accepted principle or rule that describes a particular mathematical relationship or property. These are typically proven truths, derived from axioms or basic assumptions, that hold under specific conditions. Laws often serve as foundational principles in a given field of mathematics.
• An Identity is an equality that holds true for all possible values of its variables. An identity is essentially an equation that is always true, regardless of the values substituted into it. These often come up in the context of algebraic manipulations or transformations.
• A Theorem is a mathematical statement that has been proven to be true, given a certain set of conditions. Theorems often describe more specific or derived results and are proven using axioms, other theorems, and logical deduction.

## Related Terms

In mathematics, a law refers to a universally accepted principle or rule that describes a particular mathematical relationship or property. These mathematical laws are typically proven truths, derived from axioms or basic assumptions, that hold under specific conditions.

A theorem is a statement that has been proven to be true within the framework of a mathematical system, based on the system's axioms and previously established theorems. Theorems are central to mathematics because they establish truths that we can rely on for solving problems and understanding the structure of mathematical systems.