求值cos2π/5*tan5π
求值:cos2π7
COSπ/5乘以COS2π/5
求COSπ/5*COS2π/5
arctan(tan5π/4)为什么等于arctan(-1) tan(5π/4)=tan(π+π/4)不应等于arcta
确定cos7/12π,sin(-465°),tan11/3π,sin3*cos4*tan5的符号
cosπ/5·cos2π/5等于多少?
(cosπ/5)(cos2π/5)的值等于
cosπ/5 乘以cos2π/5等于多少
已知cos2α=3/5,求值:cos^2α+sin^4α
(1)确定tan(-3)/cos8×tan5的符号;(2)已知α∈(0,π),且sinα+cosα=m(0<m<1)
cosπ/5*cos2π/5 =(2sinπ/5*cosπ/5*cos2π/5)/(2sinπ/5) =(sin2π/5
(二倍角的三角函数)cosπ/5cos2/5π的值是______cosπ/5cos2π/5 =sinπ/5cosπ/5c