2) cos19°30 cos25°30 - sin 19°30 sin25°30 3) cos 8п/7*cos - вопрос №2193025301930253038778771258798 от Nagornjk 30.09.2020 18:33

Question

Алгебра: 2) cos19°30 cos25°30 - sin 19°30 sin25°30 3) cos 8п/7*cos п/7+sin 8п/7*sin п/7

Nagornjk · Answer

2) cos a*cos b-sin a*sin b=cos(a+b) cos(19°30 +25°30 )=cos 45°=√2/2 3) cos a*cos b+sin a*sin b=cos(a-b) cos(8Π/7-Π/7)=cos Π=-1...

2) cos19°30'cos25°30' - sin 19°30'sin25°30' 3) cos 8п/7*cos п/7+sin 8п/7*sin п/7