I'm typing up some physics notes about wave interference patterns and want to include a graph of the wave produced by a 3-slit experiment:

[![enter image description here](https://i.stack.imgur.com/NNcXy.png)](https://i.stack.imgur.com/NNcXy.png)

Does anyone know what formula produces this kind of curve? I've been searching for a while but haven't found anything. I know it must be some kind of sine wave.