2017-2018学年苏教版必修四  诱导公式一~四 课时作业
2017-2018学年苏教版必修四     诱导公式一~四      课时作业第3页

  =-[asin(2 013π+α)+bcos(2 013π+β)]=1.

  答案:1

  6.解:(1)∵cos=cos=cos=,

  tan=tan=tan=1,

  ∴cos+tan=+1=.

  (2)原式=sin(60°+360°)cos(30°+2×360°)+sin[30°+(-2)×360°]cos[60°+(-2)×360°]=sin 60°cos 30°+sin 30°cos 60°

  =×+×=1.

  7.解:sin(3π+θ)=-sin θ,∴sin θ=-.

  原式=+

  =+===32.

  8.解:∵cos(105°-α)=cos[180°-(75°+α)]

  =-cos(75°+α)=-,

  sin(α-105°)=-sin(105°-α)=-sin[180°-(75°+α)]

  =-sin(75°+α).

  又cos(75°+α)=>0,α为第三象限角,

  可知角75°+α为第四象限角,

  则有sin(75°+α)=-

  =- =-.

  ∴cos(105°-α)+sin(α-105°)=-+=.