math question - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: Not HP Calculators (/forum-7.html) +--- Forum: Not remotely HP Calculators (/forum-9.html) +--- Thread: math question (/thread-5818.html) math question - Don Shepherd - 03-05-2016 03:52 PM or maths, if you are not in the US I am trying to graph circles on my TI-84 plus graphing calculator. I know that the formula for a circle is (x-h)^2 + (y-k)^2 = r^2 where the center of the circle is (h,k) and the radius is r, but to actually graph the circle I need two formulas (one for the upper part, one for the lower) in the form y1= and y2=, using variables x, h, k, and r. I have found several formulas on the Internet, but none give me the results that I would expect. RE: math question - SlideRule - 03-05-2016 04:11 PM How do I graph a circle on a TI graphing calculator? Functions can be graphed on TI graphing calculators in the form Y in terms of X. In order to graph a circle, the function for a circle would need to be solved for Y, ie to graph the unit circle (x2+y2=1), first, solve for y, and then input the results into the Y= Editor source: "Graphing a Circle on a TI Graphing Calculator. - Knowledge Base by Texas Instruments - US and Canada" BEST! SlideRule RE: math question - Manolo Sobrino - 03-05-2016 04:57 PM Why don't you try a parametric plot? Mode->Par X_{1T} = h + r*cos(T) Y_{1T} = k + r*sin(T) Zoom->ZSquare or ZDecimal or ZInteger If you insist on using Cartesian coordinates, then Mode->Func Y_{1} = k +\sqrt{r^2-(x-h)^2} Y_{2} = k -\sqrt{r^2-(x-h)^2} Zoom->ZSquare or ZDecimal or ZInteger RE: math question - Don Shepherd - 03-05-2016 05:46 PM Thanks SlideRule and Manolo, that's exactly what I was looking for. RE: math question - klesl - 03-07-2016 08:38 AM You can use following application for this task https://education.ti.com/en/us/software/details/en/6D27F3EB7E354D8DBDA5543AF744D0E3/83conicgraphing There are 4 shapes - circle, ellipse, hyperbola and parabola RE: math question - Don Shepherd - 03-07-2016 09:08 PM Thanks Klesl, that is a good reference.