Greetings. I have been teaching myself Calculus. To do this I ordered a used Larson's 8th Edition Calculus and a used TI-81 graphing calculator. When I got to Chapter 10, I ran into a problem: the chapter introduces equations in polar form and when I whipped out my TI-81, I had no idea how to graph in polar form. The used cheapo came with no instruction booklet. I have pressed every button on this calculator to see how to graph in polar form, but with no luck. I'm at a dead end here. When I depress the "Mode" button, it gives me the option of converting from rectangular form to polar form, which to me obviously implies that it can graph in polar form. At the top, I press the "Y=" button and assume that perhaps when it's in "polar form" (which I made sure to do by the "Mode" button), it assumes that "Y=" becomes "r=". Nope. It doesn't. I'm at a loss. Anyone help me out here?