Prime objective of this article is to Define and Discuss on Fundamental Identities. This article explain Fundamental Identities in Trigonometry point of view. Here explain Fundamental Identities with proper examples and graph. If an equation contains one or more variables and is valid for many replacement values of the variables for which both sides of the equation are defined, then the equation is known as an identity. The picture x 2 + 2 x = x(x + 2), for case in point, is an identity given it is valid for just about all replacement values of times (x).