So I need help with two different types of equations the first is:

Sec^2(x)-2tan^2(x)=2/3

And I need to find all solutions in the interval [0,2pi)

If you can show me how to start solving this equation would be awesome

The second equation is:

Tan(x)=-srt3/3

I understand cos and sin but not really tan I need to find all solutions and write the equation as

X=?+pik, where k is any integer

Thanks in advance guys!!