Isolate the variable/solve for $\theta$:
$$\sin (2\theta) = 4 \cos (2\theta)$$
Like which $\cos$ double angle formula would I use? Because there are three of them. Thanks in advance.
[Math] How to isolate/solve for $\theta$ in $\sin (2\theta) = 4 \cos (2\theta)$
algebra-precalculustrigonometry
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Best Answer
$$\sin { 2\theta =4\cos { 2\theta } } \\ \tan { 2\theta =4 } \\ 2\theta =\arctan { 4+k\pi } ,k\in { Z }\\ \theta =\frac { 1 }{ 2 } \arctan { 4+\frac { k\pi }{ 2 } } ,k\in { Z }$$