Texas Instruments TI-89, TI-92

162 Chapter 10: 3D Graphing

10_3D.DOC TI-89/TI-92 Plus: 3D Graphing (English) Susan Gullord Revised: 02/23/01 11:00 AM Printed: 02/23/01 4:22 PM Page 162 of 2210_3D.DOC TI-89/TI-92 Plus: 3D Graphing (English) Susan Gullord Revised: 02/23/01 11:00 AM Printed: 02/23/01 4:22 PM Page 162 of 22

The viewing angle has three components:

¦ eyeq — angle in degrees from the

positive x axis.

¦ eyef — angle in degrees from the

positive z axis.

¦ eyeψ — angle in degrees by which the

graph is rotated counterclockwise

around the line of sight set by eyeq

and eyef.

In the Window Editor ( ¥$),

always enter eyeq, eyef, and eyeψ in

degrees, regardless of the current angle

mode.

The view on the Graph screen is always oriented along the viewing

angle. From this point of view, you can change eyeq to rotate the

viewing angle around the z axis.

z1(x,y) = (x3y - y3x) / 390 In this example, eyef = 70

Rotating and/or Elevating the Viewing Angle

In 3D graphing mode, the eyeq and eyef Window variables let

you set viewing angles that determine your line of sight. The

eyeψ Window variable lets you rotate the graph around that

line of sight.

How the Viewing

Angle Is Measured

Note: When

eyeψ=0

, the

z axis is vertical on the

screen. When

eyeψ=90

the z axis is rotated 90¡

counterclockwise and is

horizontal.

Effect of Changing

eyeq

Note: This example

increments

eyeq

eyef

eyeψ

Do not enter a ¡ symbol. For example,

type 20, 70, and 0, not 20¡, 70¡, and 0¡.

eyeq = 20

eyeq = 50

eyeq = 80