Question 634881
 Find the angles of 0 degree \< x \< 360 degrees of the equation cos 4x - cos 2x = 0
===================
I would have done this one, but you were too lazy to make it clear if you mean
{{{cos(4x) - cos(2x) = 0}}}
or 
{{{cos^4(x) - cos^2(x) = 0}}}
=================
The other tutor spent his time assuming the former.
-----------
Making the problem clear is your responsibility.