sin(x)/cos(2x) cos(3x) = (sin(x)cos(3x))/(cos(2x))= (sin(x)cos(3x))/(cos(2x))= (sin(x)(cos(3x)-sin(3x)))/(cos(2x)) [Using the identity cos(a)cos(b) = (1/2)(cos(a-b) + cos(a+b)) and sin(a)cos(b) = (1/2)(sin(a+b) + sin(a-b))]= (sin(x)cos(3x) - sin(x)sin(3x))/(cos(2x))= (sin(x)cos(3x) - sin(x)sin(3x))/(cos(2x))
sin(x)/cos(2x) cos(3x) = (sin(x)cos(3x))/(cos(2x))
= (sin(x)cos(3x))/(cos(2x))
= (sin(x)(cos(3x)-sin(3x)))/(cos(2x)) [Using the identity cos(a)cos(b) = (1/2)(cos(a-b) + cos(a+b)) and sin(a)cos(b) = (1/2)(sin(a+b) + sin(a-b))]
= (sin(x)cos(3x) - sin(x)sin(3x))/(cos(2x))
= (sin(x)cos(3x) - sin(x)sin(3x))/(cos(2x))