Sina^4+2√3sinacosa-cosa^4
=√3sin2a+(sina^2+cos^2)(sina^2-cosa^2)
=√3sin2a+sina^2-cosa^2
=√3sin2a-(cosa^2-sina^2)
=2(√3/2sin2a-1/2cos2a)
=2(sin2acosπ/6-cos2asinπ/6)
=2sin(2a-π/6)