Square; Shade - Texas Instruments TI-82 Keystroke Manual

20 Calculator Keystroke Guide
To make the zoom in occur, press ENTER. The graphs are redrawn, zoomed in on the point of
interest. The graphs still appear as though they may intersect. Notice that the Zoom In cursor still
appears on the screen. To zoom in again on the place where the graphs appear to intersect, use the
arrow keys again to move the cursor over the place where the graphs appear to intersect and press
ENTER. From the resulting zoomed in view, it seems that these two graphs don't intersect after all!
If you want to zoom in again, just to be sure, follow the same procedure.
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26 Square

A set of Window settings is said to be a square setting if a one-pixel change in the x direction
(horizontal) represents the same distance as a one-pixel change in the y direction (vertical). A
square setting can eliminate distortions in the shapes of certain geometric figures. For example, in
most graphing windows a circle will appear more like an ellipse or oval shape, but in a square
setting a circle looks like a true circle. Also, perpendicular lines look truly perpendicular only in a
square setting.
To produce a square setting, just press the ZOOM key and then press 5 (ZSquare). The
graphing window you had before will be converted to a square setting. For example, enter as Y
1
the expression x
2
these two perpendicular lines in the Standard viewing window (ZOOM 6). In the Standard viewing
window these two lines certainly don't look perpendicular. Now press ZOOM 5 to produce a square
viewing window. The lines should now look much more like they are perpendicular.
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27 Shade

The Shade command shades a part of the graphing window between two graphs, or between a
graph and a given constant value of y. The density of the shading can be specified, and the
shading can also be restricted to appear between two given values of x. The Shade command asks
for at least 2 and up to 5 pieces of information to produce the kind of shading you want. The
information is entered in the following form. First, there is the Shade command itself, followed by
the five pieces of information enclosed in parentheses and separated by commas:
Shade(lower function, upper function, shading density, beginning x, ending x)
↑
required
lower function = function or constant value of y you want at the bottom of the shaded region
upper function = function or constant value of y you want at the top of the shaded region
shading density = (optional) how densely you want the shading to occur (solid = 1 to least = 8)
beginning x = (optional) smallest value of x for which you want to have shading
ending x = (optional) largest value of x for which you want to have shading
+
3 . (Enter it as Y =(1/2)X+3.) Enter as Y
1
↑ ↑
required optional
the expression
2
↑ ↑
optional optional
1
− x 2 −
. Graph
4