作业帮求4cos^2(35`)-cos(170`)-tan(160`)sin(170`)的值
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求4cos^2(35`)-cos(170`)-tan(160`)sin(170`)的值
求4cos^2(35`)-cos(170`)-tan(160`)sin(170`)的值
求4cos^2(35`)-cos(170`)-tan(160`)sin(170`)的值
原式=2(1+cos70)+cos10+tan20sin10
=2+2sin20+cos10+sin20sin10/cos20
=2+(2sin20cos20+(cos10cos20+sin20sin10))/cos20
=2+(sin40+cos10)/cos20
=2+(sin40+sin80)/cos20
=2+2sin60cos20/cos20
=2+根号3
>> 4*cos(35*pi/180)^2-cos(170*pi/180)-tan(160*pi/180)*sin(170*pi/180)
ans =
3.7321