Задача 61617 ...

61950c99c276aa24f4a0185c

17.11.2021 17:09:36

cos3x×cos4x-sin3x×sin4x=½

5f3ea7e3faf909182968ddd9

18.11.2021 00:26:32

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Формула

[r]cos α cos β -sin α sin β =cos( α + β )[/r]


[m]cos(3x+4x)=\frac{1}{2}[/m]

[m]cos7x=\frac{1}{2}[/m]

[m]7x= ± arccos( \frac{1}{2})+2πn , n ∈[/m][b] Z[/b]

[m]7x= ± \frac{π}{3})+2πn , n ∈[/m][b] Z[/b]

[m]x= ± \frac{π}{21})+\frac{2π}{7}n , n ∈[/m][b] Z[/b] - о т в е т