(√3tan12°-3)⼀sin12°(4cos²12°-2)急！！！ 最好详细说明每一步

原式=(√3sin12°-3cos12°)/[sin12°cos12°*2(2cos²12°-1)]
=[2√3(1/2*sin12°-√3/2*cos12°)]/[1/2*sin24°*2cos24°]
=[2√3sin(12°-60°)]/(1/2*sin48°)
=(-2√3sin48°)/(1/2*sin48°)
=-4√3

=2根号3*(sin12/2cos12-根号3/2)/2sin12cos24

=2根号3(sin12cos60-cos12sin60)/2cos12sin12cos24

=2根号3sin(12-60)/2cos12sin12cos24

=2根号3sin48/sin24cos24

=4根号3sin48/sin48

=4根号3.

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√3tan12-3
=√3sin12/cos12-3
=(√3sin12-3cos12)/cos12
=2√3sin(12-60)/cos12
=-2√3sin48/cos12
=-4√3sin24cos24/cos12
=-8√3sin12cos12cos24/cos12
=-8√3sin12cos24

sin12(4(cos12)^2-2)
=sin12(4(cos24+1)/2-2)
=sin12*2cos24
=2sin12cos24

所以√3tan12-3/[sin12(4(cos12)^2-2)]=-4√3