Hi Guys,
I am trying to investigate a function, during the process I need to solve this equation:
sin(x)+cos(2x)=0
in the region 0<=x<=2*Pai
How do I solve it ?
thanks !
Start by writing it as $\displaystyle \cos{2x} = -\sin{x}$ and recall that $\displaystyle \cos\left(\varphi+\frac{\pi}{2}\right) = -\sin{\varphi}$.
So we have $\displaystyle \cos{2x} = \cos\left(x+\frac{\pi}{2}\right)$. You should be able to solve it with ease now.
Hint: if $\displaystyle \cos{\theta} = \cos{\alpha}$ then $\displaystyle \theta = 2n\pi\pm \alpha$ (where $\displaystyle n$ is an integer, or zero).