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December 23rd, 2018, 06:13 AM   #1
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Limit problem


How can I solve this question without using derivatives?

Last edited by Elize; December 23rd, 2018 at 06:18 AM.
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December 23rd, 2018, 06:26 AM   #2
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Multiply numerator and denominator by $\cos x +\sqrt{\cos 2x}$.
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December 24th, 2018, 07:25 AM   #3
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Quote:
Originally Posted by v8archie View Post
Multiply numerator and denominator by $\cos x +\sqrt{\cos 2x}$.
I did still couldn't solve it
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December 24th, 2018, 08:37 AM   #4
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\begin{align}(\cos x - \sqrt{\cos 2x})(\cos x + \sqrt{\cos 2x}) &= \cos^2 x - \cos 2x \\ &= \cos^2 x - (\cos^2 x - \sin^2 x) \\ &= \sin^2 x\end{align}
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