Question

1.已知tanx=根号下3,π

Answer 1

1.分子、分母同除以cosx：

cosx-sinx=(1-tanx)/(1/cosx)

=(1-tanx)/secx.

=(1-tanx)/[±√(1+tan^2x).

=(1-√3)/{±√[1+(√3)^2]}

=-(1-√3)/2. ( π ＜x＜3π/2, cosx