一只有cc的猪
幼苗
共回答了22个问题采纳率：95.5% 举报
√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
1年前
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