Решите : 1. (tg α/ctg α) + 1 = 2. (sin^2 α - 1) / (1 - cos^2 α) =

Question

Решите :
1. (tg α/ctg α) + 1 =
2. (sin^2 α - 1) / (1 - cos^2 α) =

Answer 1

1. (tg α/ctg α) + 1 =tgα·tgα+1=tg²α+1=1/cos²α
2. (sin² α - 1) / (1 - cos² α) =(1-cos²α-1)·sin²α=-cos²α·sin²α=-4 cos²α·sin²α/4=
=-sin²2α/4