Re: Trigonometry
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Re: Trigonometry
This is a case where the calc might need a little "help" -- a
human/machine combination is pretty powerful!
Use tExpand( ) on that equation [the equivalent of applying trig
identities]. You can clean up the result by dividing by sqrt(2), and
substituting c for cos(x) and s for sin(x), to get:
2cc -2sc- sqrt(2)s -1 = 0.
Solve for s as a function of c. Square this and use the fact that ss = 1 - cc,
and you have an algebraic equation in c that you ought to be able to solve.
Then take inverse cosines.
Too much of a mess? Well, what should we expect our calculators to do
for us, anyway? We are always going to keep moving up to harder and harder
problems, which we will be able to just reach by giving our software an
intelligent boost from time to time.
RWW Taylor
National Technical Institute for the Deaf
Rochester Institute of Technology
Rochester NY 14623
>>>> The plural of mongoose begins with p. <<<<
===========================================================================================
> Roland Antaki wrote:
>
> Hi eveybody,
> I have a TI-89.I would like to solve this trigonometric equation:
> sin((pi/4)-2x)-sin(x)=0.
> I would like to know the EXACT results but the TI-89 will give me the
> approximate results only.Can anyone tell me why?
> Can't I optain the exact solutions for this equation.
> I have also found that the TI-89 is not very strong in trigo
> functions.For example you cannot optain a trigo expression
> with tan,sin,cos or what you want.
> Thank you a lot for help.
> Carl ANTAKI.
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