Texas Instruments TI-89 Titanium Short User Manual

Appendix A: Functions and Instructions 253
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 196.
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