Question

1+2/tgA+ctgA
если sinA+cosA=1/3

Answer 1

sina+cosa=1/3

1+2/(tga+ctga)=1+2/(sina/cosa+cosa/sina)=
1+2/(sin²a+cos²a)/cosa*sina=
1+2cosa*sina=sin²a+cos²a+2sina*cosa=
(sina+cosa)²=(1/3)²=1/9
ответ 1/9