# Math Help - Find the x

1. ## Find the x

$2\cos(2x)-2\sin(x)=0$
another one:

$2\sin(x)+\sin(2x)=0$

Thank you very much

2. Thank you very much but i did it exactly like you did and in the book the answers are different...
for 1:

$\frac{\pi}{6}$

$\frac{5}{6}\pi$

and for 2:
$\pi$

$2\pi$

3. Originally Posted by mathwhat
Thank you very much but i did it exactly like you did and in the book the answers are different...
for 1:

$\frac{\pi}{6}$

$\frac{5}{6}\pi$

and for 2:
$\pi$

$2\pi$
The answers you have stated here are correct for the interval from $0$ to $2\pi$

4. Originally Posted by dhiab
Small error: $\cos (2x) = 1 - 2\sin^2 (x)$ NOT $2\sin^2 (x) - 1$. So for #1 you will get pi/6 and 5pi/6 ....