章鱼buct
春芽
共回答了16个问题采纳率:81.3% 举报
sin(-1300度)=sin(3x360度+220度)=sin(180度+40度)=sin40度
sin(-7π/6)=-sin7π/6=-sin(π+π/6)=sinπ/6=1/2
cos(-79π/6)=cos(79π/6)=cos(12π+7π/6)=cos7π/6=cos(π+π/6)=-cosπ/6=-√3/2
化简
1: =-sinacosasina=-sin^2acos
2: =-sin^3acosa(-tana)=sin^4a
1年前
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