If fx)=sin3x+sin3(60∘−x)−sin3(60∘+x)
We have, sin3A=3sinA−sin3A4
Substituting in the given equation, we get
3sinx−sin3A4+3sin(60−x)−sin3(60−x)4+3sin(60+x)−sin3(60+x)4
U\sin g formula sinA−sinB=2cos(A+B2)sin(A−B2, we get
=−34sin3x
Range would be
[−34,34]
Hence, option 'C' is correct.