If cos 2theta + 3cos theta = 0, then the gene | vedclass

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Question

(a) $2{\cos ^2}	heta - 1 + 3\cos 	heta = 0$

$\cos 	heta = \frac{{ - 3 \pm \sqrt {9 + 8} }}{4} = \frac{{ - 3 \pm \sqrt {17} }}{4}$

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Vedclass · Accepted Answer

$2n\pi \pm {\cos ^{ - 1}}\frac{{ - 3 + \sqrt {17} }}{4}$

Vedclass · Answer

(a) $2{\cos ^2}	heta - 1 + 3\cos 	heta = 0$

$\cos 	heta = \frac{{ - 3 \pm \sqrt {9 + 8} }}{4} = \frac{{ - 3 \pm \sqrt {17} }}{4}$

$ \Rightarrow $ $	heta = 2n\pi \pm {\cos ^{ - 1}}\left( {\frac{{ - 3 + \sqrt {17} }}{4}} ight)$, (Taking $+ve$ sign).

If $\cos 2\theta + 3\cos \theta = 0$, then the general value of $\theta $ is

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