I need some help with the equation of an arc. I want it to be part of a perfect circular arc (not oval, etc) in the +/+ quadrant. It should start at 0, 10 and go down to 10, 0. Can someone help me out with the equation for that? Should look like the top right quarter of a circle centered around 0, 0 point. I'm a bit stuck. Really I want to put this into an Excel graph but figure I'll just use the equation to create 10 points and graph it based on that.