which shows that the zero frequency component a 0 {\displaystyle a_{0}} of f ( t ) {\displaystyle f(t)} is the average of f ( t ) {\displaystyle f(t)} over the interval [ − T , T ] . {\displaystyle [-T,T].}
![{\displaystyle [-T,T].}](https://en.wikipedia.org/api/rest_v1/media/math/render/svg/4a054d40176bb0793b7dcdeb3a3a850ae9a0ddfb)