UnitCircleQuiz and I wrote it to help people memorize the unit circle. It displays all of the angles in Radians and their corresponding coordinates within the unit circle. The timer at the top records how long it takes you to complete the unit circle and the progress bar along the bottom shows you how far through the round you are. Once completed, a high score list is shown with your best scores (percentage correct) and best times.
You can find it here: https://play.google.com/store/apps/details?id=com.chrisk.UnitCircleQuiz.
For the technically inclined: I wrote this app using QML and Qt C++, which was a pretty amazing experience! I could easily and instantly test out any screen resolution and aspect ration by debugging the QML UI file as a native application on my computer. If you're looking for a language to develop Android apps in, seriously consider QML and C++!
Thanks for stopping by!