Solve `sin 2x=4 cos x`.

Explanation

We have
`sin 2x=4 cos x`
`:. 2 sin x cos x=4 cos x`
Here, we should not cancel `cos x`.
Now, `2 sin x cos x -4 cos x=0`
`:. cos x(2 sin x-4)=0`
We have `cos x =0 or sin x=2`, which is not possible.
`:. x=(2n+1) pi/2, n in Z`
3. The solution of the equation should not contain such values of angles which make any of the terms undefined or infinite in the original equation. Domain should not change while simplifying the equation. If it changes, necessary corrections must be made.