irenemarga01
Sin 4a+sin 2a/ cos 4a+ cos 2a =(2sin 2a cos 2a+sin 2a)/ (2cos^2 2a-1+cos 2a)
= sin 2a (2 cos 2a+1)/ (2cos 2a+1)(cos 2a-1)
= sin 2a/ (cos 2a-1) = 2sin a cos a/ (2 cos^2a-1-1) = 2sin a cos a/ (2 cos ^2 a -2) = 2 sin a cos a / 2( cos^2 a-1) = sin a cos a/ -sin^2 a = cos a/-sina = -cot a
=(2sin 2a cos 2a+sin 2a)/ (2cos^2 2a-1+cos 2a)
= sin 2a (2 cos 2a+1)/ (2cos 2a+1)(cos 2a-1)
= sin 2a/ (cos 2a-1)
= 2sin a cos a/ (2 cos^2a-1-1)
= 2sin a cos a/ (2 cos ^2 a -2)
= 2 sin a cos a / 2( cos^2 a-1)
= sin a cos a/ -sin^2 a
= cos a/-sina
= -cot a