Question

Запишите в виде произведения. 1) sin 70+sin 50 2) cos 70+cos 50 3) sin 70-sin 50 4) cos 70-cos 50 Пожалуйста♥

Answer 1

2sin((70+50)/2)* cos((70-50)/2)=2sin 120/2  cos 20/2 = 2 sin60 * cos10 = √3cos10

2cos60 cos10 = cos10

2cos60* sin10 = sin10

-2sin60*sin10=- √3sin10

Answer 2

1) sin 70+sin 50 = 2sin((70+50)/2)cos((70-50)/2) = 2sin60cos10
2) cos 70+cos 50 = 2cos((70+50)/2)cos((70-50)/2) = 2cos60cos10
3) sin 70-sin 50 = 2cos((70+50)/2)sin((70-50)/2) = 2cos60sin10
4) cos 70-cos 50 = -2sin((70+50)/2)sin((70-50)/2) = -2sin60sin10