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Trignometry

Cool goIITian

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2 Apr 2008 21:36:35 IST

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364

Please explain once again.

None

Calculate the minimum value of cos2+cos for all real values of ?

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PyareMohan

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Joined: 28 Mar 2008

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2 Apr 2008 21:38:23 IST

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How is arihant trigonometry book for IIT?

Anand Hegde

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2 Apr 2008 21:40:16 IST

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dint you post the same question the other day????

sreeraman nagasubramaniyan

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2 Apr 2008 21:45:41 IST

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$\cos(2\theta)+\cos(\theta) = 2\cos^2(\theta)-1+\cos(\theta) \\ \\ \mbox{Differentiating we get} \\ \\ 4\cos(\theta) (-\sin(\theta)) - (\sin(\theta)) = 0 \\ \\ \Rightarrow (\sin(\theta)) [ 1+4\cos(\theta)] = 0 \\ \\ \cos(\theta) = \frac{-1}{4} \\ \\ \mbox{Min value is} \\ \\ = \frac{-9}{8}$

jugnu

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3 Apr 2008 09:40:39 IST

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If cos

=-1/4 then minimum value is -9/8 please prove

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