ok i'm having trouble with this problem...

i think there must be a very easy way of doing it but i'm just not getting it.....( i ended up in a huge mess)

tan(4x)=1.....sounded really easy to me!

$\displaystyle =(sin(4x))/cos(4x)$

$\displaystyle sin(4x) =2sin(2x)*cos(2x)$

$\displaystyle

sin(4x) = 2*(2sin(x)cos(x))*(cos^2(x)-sin^2(x))

$

now,

$\displaystyle sin4x = (4sinxcosx)*(cos^2x-sin^2x)$

which is

$\displaystyle

4sinx*cos^3x-4sin^3x*cosx

$

and i used the same expansion method to expand cos(4x) and tried to solve but i still don't see the answer which has to be solved algebrically

help is appreaciated...

thnx