If you want to create a presentation on your iPad or share other data with friends, family, fellow students or coworkers via a projector, you can hook your iPad up the projector a couple of different ways. One way is to use a dock connector to VGA cable and dock connector digital AV adaptor plus HDMI cable. You can also connect wirelessly through an Apple TV plus Kanex ATV pro cable and an Apple TV Plus HDMI cable.

To create a wireless connection, set up the Apple TV on your network and connect to the projector. Then, on your iPad, double tap the home button and select the Video mirror button so you can select Apple TV, using the projector in place of the TV. Some projectors will have proprietary apps you can use to quickly connect your iPad to the projector. One of these is the Epson iProjection app. This app will allow your iPad to connect to an Espon PowerLite projector wirelessly.

Source Apple Support