trigsubs - Maple Help
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trigsubs

handle trigonometric identities

 Calling Sequence trigsubs(expr) trigsubs(expr, options) trigsubs(s) trigsubs(s, expr)

Parameters

 expr - expression s - equation options - one or more options to trigsubs

Options

 • If trigsubs is called with expr as the first argument the options as follows can be specified:
 • annotate
 When the option annotate is specified trigsubs returns a list with each element labeled with its corresponding trigonometric identity.
 • trigidentity = string or list of strings
 The option trigidentity is specified as either a string of a trigonometric identity or a list of strings of trigonometric identities. When one trigonometric identity is specified trigsubs returns a list of an expression where the specified trigonometric identity has been subbed for all terms where that trigonometric identity exists. If there are multiple trigonometric identities assigned to the same name trigsubs returns a list where there is a separate expression for each trigonometric identity assigned to the trigidentity name of each term the trigonometric identity is applicable to. When of list of strings of trigonometric identities is specified for trigidentity, trigsubs returns a list of expressions where each expression has its terms substituted for the specified trigonometric identity with same behavior as when one trigonometric identity is specified, separately. If trigsubs does not know a trigonometric identity for any terms in expr of the specified trigonometric identity, expr is returned unchanged in a list.
 • subinert
 When the option subinert is specified trigsubs performs the substitution in inert form to prevent automatic simplification by Maple.

Description

 • The function trigsubs manages a table of valid trigonometric identities.
 • If trigsubs is called with the single argument $0$, it returns a set of functions known to the procedure.
 • If trigsubs is called with a single trigonometric expression expr, it returns a list of trigonometric expressions equal to expr.
 • If trigsubs is called with a single equation s which represents a trigonometric identity, it returns found if this identity belongs to the table, and not found otherwise.
 • If trigsubs is called with two arguments, it checks whether the identity s belongs to the table or not.  In the former case, the function applies this identity to expr and returns the result.  In the latter case, the function returns an error message.
 • For substitution of identities not known to this procedure, use subs.

Examples

 > $\mathrm{trigsubs}\left(0\right)$
 $\left\{{\mathrm{cos}}{,}{\mathrm{cosh}}{,}{\mathrm{cot}}{,}{\mathrm{coth}}{,}{\mathrm{csc}}{,}{\mathrm{csch}}{,}{\mathrm{exp}}{,}{\mathrm{sec}}{,}{\mathrm{sech}}{,}{\mathrm{sin}}{,}{\mathrm{sinh}}{,}{\mathrm{tan}}{,}{\mathrm{tanh}}\right\}$ (1)
 > $\mathrm{trigsubs}\left(\mathrm{cos}\left(a+bw\right)\right)$
 $\left[{\mathrm{cos}}{}\left({-}{b}{}{w}{-}{a}\right){,}{1}{-}{2}{}{{\mathrm{sin}}{}\left(\frac{{b}{}{w}}{{2}}{+}\frac{{a}}{{2}}\right)}^{{2}}{,}{{\mathrm{cos}}{}\left(\frac{{b}{}{w}}{{2}}{+}\frac{{a}}{{2}}\right)}^{{2}}{-}{{\mathrm{sin}}{}\left(\frac{{b}{}{w}}{{2}}{+}\frac{{a}}{{2}}\right)}^{{2}}{,}\frac{{1}}{{\mathrm{sec}}{}\left({b}{}{w}{+}{a}\right)}{,}\frac{{1}{-}{{\mathrm{tan}}{}\left(\frac{{b}{}{w}}{{2}}{+}\frac{{a}}{{2}}\right)}^{{2}}}{{1}{+}{{\mathrm{tan}}{}\left(\frac{{b}{}{w}}{{2}}{+}\frac{{a}}{{2}}\right)}^{{2}}}{,}\frac{{{ⅇ}}^{{I}{}\left({b}{}{w}{+}{a}\right)}}{{2}}{+}\frac{{{ⅇ}}^{{-I}{}\left({b}{}{w}{+}{a}\right)}}{{2}}{,}{\mathrm{cos}}{}\left({b}{}{w}\right){}{\mathrm{cos}}{}\left({a}\right){-}{\mathrm{sin}}{}\left({b}{}{w}\right){}{\mathrm{sin}}{}\left({a}\right)\right]$ (2)
 > $\mathrm{trigsubs}\left(\mathrm{cos}\left(w\right)=\mathrm{sin}\left(w\right)\right)$
 ${\mathrm{not found}}$ (3)
 > $\mathrm{trigsubs}\left(\mathrm{cos}\left(w\right)=\mathrm{sin}\left(w\right),1\right)$
 > $\mathrm{trigsubs}\left(\mathrm{sin}\left(2z\right)=2\mathrm{cos}\left(z\right)\mathrm{sin}\left(z\right),\mathrm{sin}\left(2z\right)\mathrm{cos}\left(z\right)\right)$
 ${2}{}{{\mathrm{cos}}{}\left({z}\right)}^{{2}}{}{\mathrm{sin}}{}\left({z}\right)$ (4)
 > $\mathrm{trigsubs}\left(\mathrm{sin}\left(x\right),\mathrm{annotate}\right)$
 $\left[{"Odd Function"}{=}{-}{\mathrm{sin}}{}\left({-}{x}\right){,}{"Double Angle"}{=}{2}{}{\mathrm{sin}}{}\left(\frac{{x}}{{2}}\right){}{\mathrm{cos}}{}\left(\frac{{x}}{{2}}\right){,}{"Reciprocal Function"}{=}\frac{{1}}{{\mathrm{csc}}{}\left({x}\right)}{,}{"Weierstrass"}{=}\frac{{2}{}{\mathrm{tan}}{}\left(\frac{{x}}{{2}}\right)}{{1}{+}{{\mathrm{tan}}{}\left(\frac{{x}}{{2}}\right)}^{{2}}}{,}{"Euler"}{=}{-}\frac{{I}}{{2}}{}\left({{ⅇ}}^{{I}{}{x}}{-}{{ⅇ}}^{{-I}{}{x}}\right)\right]$ (5)
 > $\mathrm{trigsubs}\left({\mathrm{sin}\left(x\right)}^{2}+{\mathrm{cos}\left(x\right)}^{2}-\mathrm{cot}\left(x\right),\mathrm{trigidentity}="Pythagoras"\right)$
 $\left[{1}{-}{\mathrm{cot}}{}\left({x}\right)\right]$ (6)
 > $\mathrm{trigsubs}\left({\mathrm{sin}\left(x\right)}^{2}+{\mathrm{cos}\left(x\right)}^{2}-\mathrm{cot}\left(x\right)+3,\mathrm{trigidentity}="Pythagoras",\mathrm{annotate}\right)$
 $\left[{"Pythagoras"}{=}{4}{-}{\mathrm{cot}}{}\left({x}\right)\right]$ (7)
 > $\mathrm{trigsubs}\left({\mathrm{sin}\left(x\right)}^{2}+{\mathrm{cos}\left(x\right)}^{2}-\mathrm{cot}\left(x\right)+3,\mathrm{trigidentity}="Pythagoras",\mathrm{annotate},\mathrm{subinert}\right)$
 $\left[{"Pythagoras"}{=}{\mathrm{Typesetting}}{:-}{\mathrm{_Hold}}{}\left(\left[{\mathrm{%+}}{}\left({1}{,}{\mathrm{%*}}{}\left({-}{1}{,}{\mathrm{cot}}{}\left({x}\right)\right){+}{3}\right)\right]\right)\right]$ (8)
 > $\mathrm{trigsubs}\left(\mathrm{sin}\left(x\right)-\mathrm{cos}\left(x\right),\mathrm{trigidentity}=\left["Difference","Odd Function"\right],\mathrm{annotate}\right)$
 $\left[{"Difference"}{=}\sqrt{{2}}{}{\mathrm{sin}}{}\left({x}{-}\frac{{\mathrm{\pi }}}{{4}}\right){,}{"Difference"}{=}\sqrt{{2}}{}{\mathrm{cos}}{}\left({x}{+}\frac{{\mathrm{\pi }}}{{4}}\right){,}{"Odd Function"}{=}{-}{\mathrm{sin}}{}\left({-}{x}\right){-}{\mathrm{cos}}{}\left({x}\right)\right]$ (9)
 > $\mathrm{trigsubs}\left(\mathrm{cos}\left(x\right),\mathrm{trigidentity}="Even Function",\mathrm{annotate}\right)$
 $\left[{"Even Function"}{=}{\mathrm{cos}}{}\left({-}{x}\right)\right]$ (10)

Compatibility

 • The trigsubs command was updated in Maple 2022.
 • The subinert option was introduced in Maple 2022.
 • For more information on Maple 2022 changes, see Updates in Maple 2022.