Упростите ctga - 1/1-tga + ctga-1

Question

Упростите
ctga - 1/1-tga + ctga-1

Answer 1

(cosa/sina -1):(1-sina/cosa)+ctga-1=(cosa-sina)/sina:(cosa-sina)/cosa +ctga-1=
=(cosa-sina)/sina * cosa/(cosa-sina)+ctga-1=cosa/sina+ctga-1=ctga+ctga-1=
=2ctga-1