(cos35的平方)*4-cos170-tan160*sin170(cos35的平方)*4-cos170-tan160*sin170谢谢
热心网友
(cos35的平方)*4-cos170-tan160*sin170=4*(1+cos70)/2+cos10-tan20*sin10=2+2cos70+cos10-tan20*sin10=2+2sin20+(cos10-sin20*sin10/cos20)=2+2sin20+(cos10*cos20-sin20*sin10)/cos20=2+2sin20+cos10/cos20=2+(2sin20*cos20+cos10)/cos20=2+(sin40+sin80)/cos20=2+[sin(60-20)+sin(60+20)]/cos20=2+2sin60*cos20/cos20=2+根号3
热心网友
解:(cos35的平方)*4-cos170-tan160*sin170,(式中的三角函数都省略了"度",以下同)=2(1+cos70)-cos(180-10)-tan(180-20)*sin(180-10)=2+2cos70+cos10+tan20sin10=2+2cos70+(cos10cos20+sin20sin10)/cos20=2+2cos70+cos10/cos20=2+(2cos70cos20+cos10)/cos20=2+(cos90+cos50+cos10)/cos20=2+(cos50+cos10)/cos20=2+2cos30cos20/cos20=2+√3.