# Even and odd functions - Relations and Functions

### Even and odd functions

If we are asked whether a given graph is symmetrical about the y-axis or not, it's easy to answer because we only need to see if there is a mirror image about the y-axis or not. But what if we are only given a function, but not the graph? In this section, we will broaden our knowledge about symmetry in functions while classifying symmetries algebraically, as well as learning the notion of odd and even functions.

###### Related concepts:

- Sine graph: y = sin x
- Cosine graph: y = cos x
- Definite integral