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Find the coordinate matrix of the function $\cos^2x$ relative to the ordered basis $\{1,\cos x,\sin x,\sin 2x\}$.

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    This sounds like a command, not a question. You should give us some context for your problem, as well as what your ideas are so far.2012-12-15
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    Since when are sets ordered?2012-12-15
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    @akkkk: Sets are not generally ordered, but a basis is ordered so that the co-ordinates read off the basis becomes unique.2012-12-15
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    Since $\cos^2(x)$ is even and has period $\pi$ it is not an exact linear combination of the basis elements. If this is about approximation then this question needs more context.2012-12-15
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    I see that {1,sinx,cosx} generates cos^2 but how ı can find coordinate matrix?2012-12-15
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    @signum Then you see more than I do.2012-12-15
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    I don't think that given functions form a basis, since last element depends on third and second as $\sin 2x = 2 \sin x \cos x$2012-12-15
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    @Kaster How's that a linear dependency?2012-12-15
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    @WimC I don't understand your question.2012-12-15
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    OK, gotcha, those are linearly independent. My bad.2012-12-15
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    Should that $\sin 2x$ maybe be $\sin^2 x$?2012-12-15

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