(1)sin(-5π/12) (2)cos(-61π/12)
问题描述：
(1)sin(-5π/12) (2)cos(-61π/12)
答
(1)sin(-5π/12)=-sin(5π/12)=-cosπ/12=-√[(cosπ/6+1)/2]=-√[(√3+2)/4]=-(√6+√2)/4 (2)cos(-61π/12)=cos(-5π-π/12)=-cos(-π/12)=-cosπ/12=-(√6+√2)/4