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复数z=-sinπ/7-icosπ/7的弧角主值是

题目详情
复数z=-sinπ/7-icosπ/7的弧角主值是
▼优质解答
答案和解析
z=-sinπ/7-icosπ/7
=cos(3π/2-π/7)+isin(3π/2-π/7)
=cos(19π/14)+isin(19π/14)
argz=19π/14
诱导公式sin(3π/2-θ)=-cosθ
cos(3π/2-θ)=-sinθ