TI 84 Parametric Equations

TI 84 Parametric Equations are easy to graph. You can even see them in a table. First, you’ll likely have to adjust to thinking in terms of parametric equations. Most of us have been drilled into thinking in terms of rectangular functions. For us, we set y in terms of x. And that’s that.

Now, with parametric equations, a third variable has entered the mix. Once you understand the relationships between the variables, your TI 84 parametric equations will start to make more sense.

[embedyt] https://www.youtube.com/watch?v=NSK0ocsbWN0[/embedyt]

TI 84 Parametric Equations Example 1

Sometimes you learn best by example. So, here’s your example. It’s a basic parametric equation and will show you how to assign expressions to each variable. Basically, both x and y are dependent variables. That means they are in terms of another variable. For parametric equations, x and y are usually in terms of t.

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[embedyt] https://www.youtube.com/watch?v=MkmL-xc_3os[/embedyt]

More Complicated Parametric Equation

For this example, you have both x and y in terms of t-squared. You’re probably used to having y in terms of x-squared. In rectangular coordinates, that’s a parabola.

Now, with both x and y in terms of t-squared, it can still be a parabola. Sometimes it won’t be, sometimes it will be. In this particular example, you still have a parabola. Unlike rectangular coordinates, this graph won’t be a function as it doesn’t pass the vertical line test.

Oh, one last thing: you’ll likely have to keep changing the viewing window. Instead of relying on the default values, you sometimes will have to change the viewing window. I recommend you change the viewing window manually. While it may take a few tries to get it right, it’s worth knowing how to tweak your window until the graph fits.

Good luck!

[embedyt] https://www.youtube.com/watch?v=-Vq9j0lw8ak[/embedyt]

TI 84 Parametric Equations Example 3

Ah, now we have something a bit complicated. Now, both x and y are in terms of trig functions of t. You’ll encounter this a lot if you have more complicated parametric functions to graph.

Again, please use the table to help you understand how the graph looks. Viewing the table first can help you reset the viewing window. Just a tip.

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[embedyt] https://www.youtube.com/watch?v=OdD_cGALbOg[/embedyt]


By Martin

Martin McSweeney is a National Merit Finalist, Pomona College Graduate, and member of MENSA. He has worked at the Center for Talented Youth (Loyola Marymount University campus); Upward Bound (Harvey Mudd campus); various test prep companies; and Whittier High School. Now, Martin helps students of all abilities improve their relationship with math.