Question

设y=1+cosx / 1-cosx,求dy / dx

Answer 1

y=(1+cosx)/(1-cosx)

dy/dx=[(-sinx)(1-cosx)-(1+cosx)(sinx)]/(1-cosx)^2

=[-sinx+sinxcosx-sinx-sinxcosx)/(1-cosx)^2

=-2sinx/(1-cosx)^2