arctan［根号下（5加上2倍根号5）］，用弧度制表示几分之几π

更新时间：2022-02-01 05:29:29 138次访问

arctan［根号下（5+2倍根号5）］=

arctan√(5+2√5)=2π/5

arctan√(5+2√5)

=arcsec√[√(5+2√5)²+1]

=arcsec√(6+2√5)

=arcsec(√5+1)

=arccos[1/(√5+1)]

=arccos[(√5-1)/4]

=2π/5