Hacking the Unit Circle on the TI 84 Plus CE Graphing Calculator

Why memorize the unit circle when the exact values are at your fingertips on your calculator?? Watch this video for a quick and dirty way to summon up the exact values of trigonometric ratios. Feel free to pause the video frequently in order to pick your jaw up off the floor. And be sure to watch to the end in order to know what to do when your exact value ends up being negative!