Today, we spent most of class on discussing conceptual questions concerning the diffraction and interference of light. However, I started by introducing the small angle approximation which is helpful when solving many double-slit problems. Students were surprisingly unaccepting of the validity of this approximation, I suppose to the credit of their math teachers. I wanted to show them how good this approximation was, so I fired up Desmos and made a quick graph:
A couple students say they will still solve these problems “long-hand” as a matter of principle.