利用和（差）角公式求下列各三角函数的值.1 cos（（-61/12）π）=____________2 tan((35π)/12)=_数学解答

利用和（差）角公式求下列各三角函数的值.
1 cos（（-61/12）π）=____________
2 tan((35π)/12)=____________________

人气：384 ℃　时间：2020-02-05 12:43:50

解答

1、
原式=cos(-3*π+11π/12)
=cos(11π/12)
=cos(π/4+2π/3)
=cosπ/4cos2π/3-sinπ/4sin2π/3
=-(√6+√2)/4
2、
原式=tan(3π-π/12)
=tan(-π/12)
=tan(π/4-π/3)
=(tanπ/4-tanπ/3)/(1+tanπ/4tanπ/3)
=-2+√3