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Solve $2\cos (2\theta) = 4\sin\theta$ for all values of $\theta$ between $0^{\circ}$ and $360^{\circ}$.

I have already tried to solve this but I am unsure as to finding out this particular one.

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closed as off-topic by Did, Dominik, Henrik, Vladhagen, Leucippus Jan 13 '17 at 0:23

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$$4\sin\theta=2\cos2\theta=2(1-2\sin^2\theta)$$

$$\iff2\sin^2\theta+2\sin\theta-1=0$$ which is a Quadratic Equation in $\sin\theta$

Remember for real $\theta,-1\le\sin\theta\le1$

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  • $\begingroup$ Thank you is there any chance you could show the working out as I have a question that I similar $\endgroup$ – user406301 Jan 12 '17 at 10:26
  • $\begingroup$ @user406301, Do you know how to solve a Quadratic Equation? $\endgroup$ – lab bhattacharjee Jan 12 '17 at 10:27
  • $\begingroup$ And no I'm unsure $\endgroup$ – user406301 Jan 12 '17 at 10:39

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