haodong123
幼苗
共回答了22个问题采纳率:95.5% 举报
2.sin10°分之1-cos10°分之根号3
=1/sin10°-√3/cos10°
=(cos10°-√3sin10°)/(sin10°cos10°)
=(1/2cos10°-√3/2sin10°)/(1/2sin10°cos10°)
=sin(30°-10°)/(1/4sin20°)
=4
3.tan70°cos10°(根号3tan20°-1)
=cot20°cos10°(√3tan20°-1)
=cos10°(√3-cot20°)
=cos10°(√3sin20°-cos20°)/sin20°
=2cos10°sin(20°-30°)/sin20°
=-2sin10°cos10°/sin20°
=-1
1年前
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