# Integration Trick: $$\frac{\sin(\theta)}{\theta} = \frac{1}{2} \int_{-1}^{1} \mathrm{e}^{i\theta x} dx$$

The substitution

\frac{\sin(\theta)}{\theta} = \frac{1}{2} \int\limits_{-1}^{1} \mathrm{e}^{i\theta x} dx

comes in handy from time to time. A good example of how it is used can be found here.