Texas Instruments TI-89 Manual Book page 180

Effect of Changing
eyef
Note: This example starts
on the xy plane ( eyef = 90 )
and decrements eyef by 20
to elevate the viewing angle.
Effect of Changing
eye
Note: During rotation, the
axes expand or contract to
fit the screen's width and
height. This causes some
distortion as shown in the
example.
z=10
When eye =0 ,
the z axis runs
the height of the
screen.
z=ë10
When eye =90 , the z axis
runs the width of the screen.
z=10 z=ë10
As the z axis rotates 90¡, its
range (ë 10 to 10 in this
example) expands to almost
twice its original length.
Likewise, the x and y axes
expand or contract.
From the Home
Screen or a Program
By changing eyef, you can elevate your viewing angle above the xy
plane. If
90 < eyef < 270
y - y
3 3
z1(x,y) = (x
The view on the Graph screen is always oriented along the viewing
angles set by and
eyeq
around that line of sight.
3 3
z1(x,y)=(x yì y
The values are stored in the system variables
eye
eye . You can access or store to these variables as necessary.
: To type f or
TI-89 ,
You can also press 2 ¿ and use the Greek menu.
: To type f or
TI-92 Plus
You can also press 2 ¿ and use the Greek menu.
, the viewing angle is below the xy plane.
x) / 390 In this example, eyeq = 20
eyef = 90
eyef = 70
eyef = 50
. You can change
eyef
x) / 390 eyeq=20 and eyef=70
eye =0
eye =45
eye =90
press ¥ c j or ¥ c
[F]
press 2 or 2
, G F
Chapter 10: 3D Graphing
to rotate the graph
eye
In this example,
, , and
eyeq eyef
, respectively.
Ú
respectively.
G Y
163