cos派/5cos2派/5的值等于?

题目详情

cos派/5cos2派/5的值等于?

▼优质解答

答案和解析

cosπ/5cos2π/5
=sinπ/5cosπ/5cos2π/5 ÷ sinπ/5
=1/2sin2π/5cos2π/5 ÷ sinπ/5
=1/4sin4π/5÷sinπ/5
=1/4sinπ/5÷sinπ/5
=1/4

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