Question

求f(x)=cos²x/1-sinx的单调性

Answer 1

f(x)=(1-sin²x)/(1-sinx)

=(1+sinx)(1-sinx)/(1-sinx)

=1+sinx

所以（-π/2+2kπ,π/2+2kπ）为单调增,（π/2+2kπ,3π/2+2kπ）为单调减