Texas Instruments TI-89, TI-92

Appendix A: Functions and Instructions 513

8992APPA.DOC TI-89 / TI-92 Plus: Appendix A (US English) Susan Gullord Revised: 02/23/01 1:48 PM Printed: 02/23/01 2:21 PM Page 513 of 132

tExpand() MATH\Algebra\Trig menu

tExpand(expression1) ⇒ expression

Returns an expression in which sines and

cosines of integer-multiple angles, angle

sums, and angle differences are expanded.

Because of the identity (sin(x))2+(cos(x))2=1,

there are many possible equivalent results.

Consequently, a result might differ from a

result shown in other publications.

Sometimes tExpand() will accomplish your

goals when the default trigonometric

simplification does not. tExpand() tends to

reverse transformations done by tCollect().

Sometimes applying tCollect() to a result from

tExpand(), or vice versa, in two separate steps

simplifies an expression.

Note: Degree-mode scaling by p/180

interferes with the ability of tExpand() to

recognize expandable forms. For best results,

tExpand() should be used in Radian mode.

tExpand(sin(3f)) ¸

4øsin(f)ø(cos(f))

ìsin(f)

tExpand(cos(aìb)) ¸

cos(a)øcos(b)+sin(a)øsin(b)

Text CATALOG

Text promptString

Displays the character string promptString

dialog box.

If used as part of a Dialog...EndDlog block,

promptString is displayed inside that dialog

box. If used as a standalone instruction, Text

creates a dialog box to display the string.

Text "Have a nice day." ¸

Done

Then See If, page 456.

Title CATALOG

Title titleString, [Lbl]

Creates the title of a pull-down menu or

dialog box when used inside a Toolbar or

Custom construct, or a Dialog...EndDlog

block.

Note: Lbl is only valid in the Toolbar

construct. When present, it allows the menu

choice to branch to a specified label inside

the program.

Program segment:

:Dia

:Tit

e"T

is is a

ox"

:Request "Your name",Str

:Drop

own "Mont

you were

orn",

seq

(

string

(

)

,i,

)

,Var

:En