Question

Помогите срочно по алгебре 10 класс



tg b (1+ 1/cos2b)

Answer 1

tgb(1+1/cos2b)=tgb•(1+cos2b)/cos2b=
tgb•2cos^2(b)/cos2b=sinb/cosb•2cos^2(b)/
cos2b=2sinb•cosb/cos2b=sin2b/cos2b=
tg2b