Hi this is Rob. I am going to show you how
to graph a horizontal ellipse on the TI84 Plus CE Graphing Calculator. To graph an ellipse on the TI84 Plus CE we
are going to use the Conics App that is built into the calculator. To open the Conics App,
press the apps button here. The Applications list opens up. Go down to number 4, Conics
and press enter. The types of conics that you can graph with the Conics App are circles,
ellipses, hyperbolas and parabolas. Go down to number 2, Ellipse and press the
enter key. Now we see two standard equations for an ellipse. The first equation is for
a horizontal ellipse and the second equation is for a vertical ellipse. This video covers graphing a horizontal ellipse,
but first let’s review the parts of a horizontal ellipse. We will work with the x and y axis.
There is our horizontal ellipse in blue. We have a center of an ellipse. Then along the
major axis of the ellipse we have the vertexes at each end of the major axis. At the end
of the minor axis we have the co-vertexes. There are two focus points along the major
axis. The distance from the center to one of the vertexes is a. The distance from the
center to one of the co-vertexes is b. The distance from the center to one of the focus
points is c, and c squared equals a squared minus b squared. Remember the center is at
the coordinates h, k. The standard equation for a horizontal ellipse is x minus h squared
divided by A squared plus y minus k squared divided by b squared equals 1. Going back to the calculator. Let’s choose
one for the horizontal ellipse and press enter. This screen appears. To graph the ellipse
we will need to know a, b, h, and k from the equation of the ellipse. For our equation
we will use x minus 4 squared divided by 25 plus y minus 2 squared divided by 9 equals
1. Thus, a squared equals 25. Take the squared
root of each side. A equals plus or minus 5. B squared equals 9.
Take the squared root of each side. B equals plus or minus 3. H equals 4 and k equals 2.
Now let’s plug in these numbers into the calculator. A equals 5. Now use the down arrow key and
go to b. And enter 3 for b. Go down to h. Enter 4 for h. Go down to k. Enter 2 for k.
Now press this graph button here to graph the ellipse. Unfortunately the numbers of the graph are
not labeled. But you can press this trace button here and then use the right arrow button
to trace around the ellipse and display the coordinates on the ellipse. This is useful
to find the coordinates of the vertexes and co-vertexes of the ellipse. As you trace around
the ellipse the x and y coordinates appear at the bottom of the screen. Right now one
of the vertexes is located at x equals 9 and y equals 2. Now I will move to one of the co-vertexes
on top, remember the co-vertexes are located on the minor axis of the ellipse. And there
is one at x equals 4 and y equals 5. Ok that is it. That is how to graph a horizontal
ellipse on the TI84 Plus CE Graphing Calculator. If you like this video, please give it a thumbs
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