Posted by greg on Monday, December 3, 2012 at 10:19am.
sin2x + sin4x = 2sin3x cosx
cos2x + cos4x = 2cos3x cosx
so, we have
sin3x cosx = cos3x cosx
tan3x = 1
so, 3x = pi/4 or 5pi/4
x = pi(1+4k)/12 for all 0<=k<=5
also x=k*pi/2 (where cosx = 0)
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