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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))
¸
4
ø
sin(f)
ø
(cos(f))
ñ
ì
sin(f)
tExpand(cos(a
ì
b))
¸
cos(a)
ø
cos(b)+sin(a)
ø
sin(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
l
og
:Tit
l
e"T
h
is is a
d
ia
l
og
b
ox"
:Request "Your name",Str
1
:Drop
d
own "Mont
h
you were
b
orn",
seq
(
string
(
i
)
,i,
1
,
1
2
)
,Var
1
:En
d
D
l
og
©