Question 1056706
using identities, we have:
sin(3x) = sin(2x+x) = sin(2x)cos(x) + sin(x)cos(2x)
and sin(2x) = 2sin(x)cos(x); cos(2x) = 2cos^2(x) - 1
so sin(3x) = 2sin(x)cos(x)*cos(x) + sin(x)(2cos^2(x) - 1) -> sin(x)(2cos^2(x)+2cos^2(x) - 1) -> sin(x)(4cos^2(x)-1)