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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
\begin{equation}
X_{1T} = h + r*cos(T)
\end{equation}
\begin{equation}
Y_{1T} = k + r*sin(T)
\end{equation}
Zoom->ZSquare or ZDecimal or ZInteger
\begin{equation}
X_{1T} = h + r*cos(T)
\end{equation}
\begin{equation}
Y_{1T} = k + r*sin(T)
\end{equation}
Zoom->ZSquare or ZDecimal or ZInteger
If you insist on using Cartesian coordinates, then
Mode->Func
\begin{equation}
Y_{1} = k +\sqrt{r^2-(x-h)^2}
\end{equation}
\begin{equation}
Y_{2} = k -\sqrt{r^2-(x-h)^2}
\end{equation}
Zoom->ZSquare or ZDecimal or ZInteger
\begin{equation}
Y_{1} = k +\sqrt{r^2-(x-h)^2}
\end{equation}
\begin{equation}
Y_{2} = k -\sqrt{r^2-(x-h)^2}
\end{equation}
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.