Scatter Plots - Texas Instruments TI-92 Getting Started

Technology Tip: The automatic left parenthesis that the TI-92 places after functions such as sine, cosine, and
tangent (as noted in Section 5.1.3) can affect the outcome of calculations. In the previous example, the degree sign
must be inside of the parentheses so that when the TI-92 is in radian mode, it calculates the tangent of 45 degrees,
rather than converting the tangent of 45 radians into an equivalent number of degrees. Also, the parentheses around
π
the fraction are required so that when the TI-92 is in radian mode, it converts
6
converting merely the 6 to radians. Experiment with the placement of parentheses to see how they affect the result of
the computation.
5.4.2 Graphs of Trigonometric Functions: When you graph a trigonometric function, you need to pay careful
attention to the choice of graph window. For example, graph
along the curve to see where it is. Zoom in to a better window, or use the period and amplitude to establish better
WINDOW values.
Technology Tip:. Since π ≈ 3.1, when in radian mode, set xmin = 0 and xmax = 6.2 to cover the interval from 0 to
2π.
Next graph y = tan x in the standard window first, then press F2[Zoom] 7[Zoom Trig] to change to a special
window for trigonometric functions in which the horizontal increment is
to 4. The TI-92 plots consecutive points and then connects them with a segment, so the graph is not exactly what
you should expect. You may wish to change the plot style from Line to Dot (see Section 5.2.3) when you plot the
tangent function.
5.5.1 Entering Data: The table shows the total prize money (in millions of dollars) awarded at the Indianapolis 500
race from 1981 to 1989. (Source: Indianapolis Motor Speedway Hall of Fame.)
Year 1981
Prize $1.61
($million)
We'll now use the TI-92 to construct a scatter plot that represents these points and find a linear model that
approximates the given data.
The TI-92 holds data in lists. You can create as many list names as your TI-92 memory has space to store. Before
entering data, clear the data in the lists that you want to use. To delete a list press 2nd VAR-LINK. This will display
the list of folders showing the variables defined in each folder. Highlight the name of the list that you wish to delete
2 3
Graphing Technology Guide: TI-92
Figure 5.65: Angle measure

5.5 Scatter Plots

1982 1983 1984
$2.07 $2.41 $2.80
Copyright © Houghton Mifflin Company. All rights reserved.
π
into radians, rather than
6
sin 30 x
y =
in the standard viewing rectangle. Trace
30
π
or 7.5° and the vertical range is from –4
24
1985 1986 1987
$3.27 $4.00 $4.49
1988 1989
$5.03 $5.72