Задача 12500 (1/1-tgx - 1/1+tgx)(cos^2x-sin^2x)...

mari_nuzhnaya

23.12.2016

(1/1-tgx - 1/1+tgx)(cos^2x-sin^2x)

SOVA

23.12.2016

★

(1/(1–tgx)) – (1/(1+tgx))=(1+tgx-1+tgx)/(1-tg^2x)=

=2tgx/(cos^2x-sin^2x)/cos^2x=

=(2sinx*cosx)/(cos^2x-sin^2x)


(1/(1–tgx)) – (1/(1+tgx))*(cos^2x-sin^2x)=

=(2sinx*cosx)*(cos^2x-sin^2x)/(cos^2x-sin^2x)=

=sin2x