1-2sin^2 l+ cos^2l = (sin l - cos l)^2= (1 - cos2l)*ctg - вопрос №1222212180206 от LyubovR 21.02.2022 21:44

Question

Алгебра: 1-2sin^2 l+ cos^2l = (sin l - cos l)^2= (1 - cos2l)*ctg l =

LyubovR · Answer

1. (1 - 2sin² L)+ cos² L = cos 2L + 1/2 + 1/2 cos 2L = 0,5·(3cos 2L + 1)

2. (sin L - cos L)² = sin² L - 2sin L· cos L+ cos² L = 1 - 2sin L· cos L = 1 - sin 2L

3. (1 - cos2L)·ctg L = 2sin² L·cos L/sin L = 2sin L·cos L = sin 2L