Question

1) tg2/7 ctg2/7 -sin^2 y
2)tg2 b -( 2cos^2 b - 1)/2sin^2 b - 1

Answer 1

1) 1 - Sin² y = Cos²y
2) tg 2b - Cos 2b/-Сos 2b= tg 2b +1