How do you graph a circle with the TI-83 plus calculator?

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August 7th 2011, 08:19 PM
benny92000

How do you graph a circle with the TI-83 plus calculator?

The equation is x^2 + y^2 = 9
August 7th 2011, 08:56 PM
Bacterius

Re: How do you graph a circle with the TI-83 plus calculator?

There are different ways to do it.

Cartesian method (y = f(x))

You will need two functions because of the limitations of the cartesian coordinate system, obtained by rearranging the circle equation in terms of x:

$y = \sqrt{9 - x^2}$ and $y = - \sqrt{9 - x^2}$

Polar method

This one is simple.. $r = 3$ , since the radius of a circle is constant.

Parametric method

Use the trigonometric functions $X_t = 3 \cos{(t)}$ and $Y_t = 3 \sin{(t)}$ .

You can change the type of graphing method in the setup menu of your TI.
August 7th 2011, 11:15 PM
benny92000

Re: How do you graph a circle with the TI-83 plus calculator?

What is the preferred method?
August 7th 2011, 11:23 PM
Bacterius

Re: How do you graph a circle with the TI-83 plus calculator?

Umm.. whichever, they all produce the same circle. It's up to personal preference and context.

I would personally recommend the parametric method because it's easy to change the center of the circle if you need to (as well as the radius of course).
August 7th 2011, 11:24 PM
mr fantastic

Re: How do you graph a circle with the TI-83 plus calculator?

Quote:

Originally Posted by benny92000

What is the preferred method?

The prefered method depends on:

1. The circumstances.

2. What you prefer.

Personally, I don't see why a student would need a calculator to draw the graph of a circle.