cosπ/5 乘以cos2π/5等于多少
来源：学生作业帮助网 编辑：六六作业网 时间：2024/12/18 16:43:50
cosπ/5乘以cos2π/5等于多少cosπ/5乘以cos2π/5等于多少cosπ/5乘以cos2π/5等于多少这一类题可用对称法：设sinπ/5×sin2π/5=mcosπ/5×cos2π/5＝n
cosπ/5 乘以cos2π/5等于多少
cosπ/5 乘以cos2π/5等于多少
cosπ/5 乘以cos2π/5等于多少
这一类题可用对称法：
设sinπ/5×sin2π/5=m
cosπ/5×cos2π/5＝n
则4mn=(2sinπ/5×cosπ/5)×(2sin2π/5×cos2π/5)
=sin2π/5×sin4π/5
= sin2π/5×sinπ/5=m
∴n=1/4
即cosπ/5×cos2π/5＝1/4
cosπ/5×cos2π/5
=(2sinπ/5×cosπ/5×2cos2π/5)/(4sinπ/5)
=(2sin2π/5×cos2π/5)/[4sin(π-π/5)]
=sin4π/5/(4sin4π/5)
=1/4
cosπ/5 乘以cos2π/5等于多少
COSπ/5乘以COS2π/5
cosπ/5·cos2π/5等于多少?
（cosπ/5）（cos2π/5)的值等于
cosπ/5*cos2π/5的值等于
cos2π等于多少?
求COSπ/5*COS2π/5
cosπ/5×cos2π/5=
cosπ/5×cos2π/5
cosπ/5cos2π/5
cosπ/5cos2π/5=?
计算cos∏/5乘以cos2∏/5的值.
cosπ/5 - cos2π/5 怎样变成 cosπ/5 + cos2π/5rt
cos2π/3等于多少
cosπ/5乘以cos2π/5的值是多少?请给出具体解题过程,谢谢拜托各位大神
cosπ/5*cos2π/5的值等于 A1/4 B1/2 C2 D4
化简cosπ/5cos2π/5RT.
若cos(π-θ)=3/5,cos2θ=