Note that the TI-83 and the TI-83 plus have slightly different keys. This page uses the
keys associated with the TI-83. The differences are
that the TI-83 ![]() ![]() ![]() ![]() |
Please note that the calculator used to produce the graphs on this page had just been used to produce the graphs and screen images from the web page 238301.htm. As a result there is some residual material on this calculator.
![]() | Figure 1 is taken from the Y= screen on a TI-83 after we have defined the two functions. The first function is a straight line, and the second is a quadratic which will be graphed as a parabola. |
![]() |
Pressing ![]() |
![]() | To make the parabola appear as connected points, we use the
![]() ![]() ![]() |
![]() | Now that the option is set as we want it, we press
![]() |
![]() | Here the parabola is connected, but we still have those
plotted points left over from some earlier work, and the WINDOW limits are not clear.
We will use the ZOOM feature to set the WINDOW ranges to a more standard setting.
Press ![]() |
![]() | We press ![]() |
![]() | The standard window settings gie us a better view of the line and
of the parabola. With the new window settings, only two of the plotted
points are visible on the screen. To clear those points we need to turn off the
statistical plot. To do that we move to
the STAT PLOT menu.
Press the ![]() ![]() |
![]() | Now we can see that Plot1 is indeed On. The
easiest remedy will be to turn off
all of the plots. We do this by using the ![]() |
![]() | Once the command has been pasted onto the window, we press
![]()
Then, we return to the graph by pressing |
![]() | In Figure 10 we finally see the graph without the distracting
plotted points. Our purpose here is to use the intersect command to find the two points of intersection. We could modify the WINDOW settings to have the graph come close to the one presented in the text, but that will not be necessary. |
![]() | To get to the intersect option we need to use
![]() ![]() ![]() |
![]() | intersect goes through a number of steps. First, we need to choose the two curves to
use. It is possible that we would have more than 2 curves graphed at the same time.
The calculator wants us to choose the two graphs to use. This seems a bit superfluous
here given that there are only two functions on this graph. However, we will
have to play along with the calcualtor.
The TI-83 is proposing the first function as one of the two curves.
We press |
![]() | In Figure 13 the TI-83 proposes the second function as the the second curve.
Again, press ![]() |
![]() | Now the calculator is asking for a Guess, and it is proposing
the point ![]() |
![]() | In Figure 15 we have a Guess that is reasonably close to the
left point of intersection.
We press ![]() |
![]() | The TI-83 has determined that the left point of
intersection is Now we want to obtain the coordinates of the other point of intersection. To do this we step through the same sequence of screens, but changing our Guess so that it is close to the right point of intersection. |
![]() | To return to the intersect option we use
![]() ![]() ![]() |
![]() | The calculator proposes the first curve as one of the two curves to use.
We use the ![]() |
![]() | The calculator proposes the second curve as the other curve to use.
We use the ![]() |
![]() | The TI-83 proposes a point to use as the Guess. We do not
want to use that guess because it is too close to the left point
of intersection.
Therefore, we will use the ![]() |
![]() | In Figure 21 the new Guess point has been set. Press ![]() |
![]() | intersect has done its work. The right point of intersection
is identified as |
PRECALCULUS: College Algebra and Trigonometry
© 2000 Dennis Bila, James Egan, Roger Palay