Texas Instruments TI-89 Titanium User Manual

Appendix A: Functions and Instructions 861
tCollect() MATH\Algebra\Trig menu
tCollect( expression1 ) ⇒ expression
Returns an expression in which products and
integer powers of sines and cosines are converted
to a linear combination of sines and cosines of
multiple angles, angle sums, and angle differences.
The transformation converts trigonometric
polynomials into a linear combination of their
harmonics.
Sometimes
tCollect() will accomplish your goals
when the default trigonometric simplification does
not.
tCollect() tends to reverse transformations
done by
tExpand() . Sometimes applying tExpand()
to a result from tCollect() , or vice versa, in two
separate steps simplifies an expression.
tCollect((cos(a))^2) ¸
cos(2ø a) + 1
2
tCollect(sin(a)cos(b)) ¸
sin(aì b)+sin(a+b)
2
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)) ¸
4ø sin(f)ø (cos(f))ñìsin(f)
tExpand(cos(aì 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 805.
timeCnv() CATALOG
timeCnv( seconds ) ⇒ list
Converts seconds to units of time that can be more
easily understood for evaluation. The list is in
{
days,hours,minutes,seconds } format.
Note: See also
checkTmr() and startTmr() .
timeCnv(152442117)
{1764 9 1 57}

Texas Instruments TI-89 Titanium Specifications

General

Brand	Texas Instruments
Model	TI-89 Titanium
Category	Calculator
Language	English