-1
$\begingroup$

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In the second question, beyond this step I am stuck. enter image description here

Any hints??

  • 0
    Express all elements of $x_n$ using only $\theta_0$ – 2017-02-25
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    Don't use images as main content of your post. This makes your question impossible to search and inaccessible to the visually impaired. Please transcribe text and mathematics (note that you can [use LaTeX](http://meta.math.stackexchange.com/q/5020/)) and don't forget to give proper attribution to your sources. Ref: http://meta.math.stackexchange.com/a/20334/290189 – 2017-02-25

2 Answers 2

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Hint : $\prod_{k=1}^n \cos {2^k \theta}$ = $\dfrac 1{2^n}\dfrac {\sin 2^{n+1}\theta}{\sin \theta}$

If you are still unable to solve, drop a comment.

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Let $x_0=\cos\alpha_0$ and we get the answer: $\arccos{x_0}$