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幼苗
共回答了20个问题采纳率：95% 举报
(1) cos(-1109°=cos1109 °.
=cos(3*360 °+29°).
=cos29°.
( =0.8746).
(2)sin(-1050)=-sin1050.
=-sin(1080°-30°).
=-sin(3*360°-30).
=-(-sin30°.
=sin30.
=1/2.
（ =0.50°）.
(3) tan(19π/3)=tan(6π+π/3).
=tan(3*2π+π/3).
=tanπ/3.
=√3.
( =1.732).
1年前
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