Hi folks,

you can see that I have posted quite a few trig questions recently, so I should have it by now!

But sadly no!

say I have cos 2x = 0 and I want the general solution.

$2x = cos^{-1}(0) = 90$ and 270 degrees

so $2x = \dfrac{\pi}{2} + n\pi$ where $n \in \mathcal{Z}$

therefore $x = \dfrac{\pi}{4} + \dfrac{n\pi}{2}$

but this is wrong!

The answer is $n\pi+ \dfrac{\pi}{4}$

in my answer, I put the general term in before dividing by 2 and this seems the way you guys have been doing it in previous posts.

So what's wrong this time?