trigonometric equations



Jos Simons wrote:
> L.S.,
>  
> How can I solve with Maxima the equation
>  
> cos(2*x) =1/2 - sin(x)
>  
> in such a way that I get the exact solutions
> 3/10 pi, 7/10 pi, 11/10 pi, 19/10 pi, etc.
>  

trigexpand(%);
subst(1-sin(x)^2,cos(x)^2,%);
solve(%,x);

gets
[x=-asin(sqrt(5)/4-1/4),x=asin(sqrt(5)/4+1/4)]

you can also take the original equation and do
%,exponentialize;
solve(%,x)

and get answers in terms of logs and radicals.