Question

90 баллов, математика!

Answer 1

1) (sin²a+tg²a-sin²a)×ctga= tg²a×(1/tga)=tga

2(sin²a-1)/cos²a+tg²a= -(1-sin²a)/cos²a+tg²= -cos²a/cos²a+tg²a= -1+tg²a