(tan12-√3)/(4cos^2 12-2)sin12=

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(tan12-√3)/(4cos^212-2)sin12=(tan12-√3)/(4cos^212-2)sin12=(tan12-√3)/(4cos^212-2)sin12=tan12-√3=sin1

(tan12-√3)/(4cos^2 12-2)sin12=
(tan12-√3)/(4cos^2 12-2)sin12=

(tan12-√3)/(4cos^2 12-2)sin12=
tan12-√3=sin12/cos12-√3
=(sin12-√3cos12)/cos12
=2sin(12-60)/cos12
=-2sin48/cos12
=-4sin24cos24/cos12
=-8sin12cos12cos24/cos12
=-8sin12cos24
sin12*(4(cos12)^2-2) =sin12*(4(cos24+1)/2-2)
=sin12*2cos24
=2sin12cos24
(tan12-√3)/(4cos^2 12-2)sin12=-4