Предмет: Алгебра, автор: PhilTed

Помогите пожалуйста ! 5cos2x+9sinx-7=0

Ответы

Автор ответа: Simba2017

сos2x=1-2sin^2x
5-10sin^2x+9sinx-7=0
sinx=t
-10t^2+9t-2=0
D=81-80=1
t1=(9+1)/(-10)=-1; sinx=-1; x=pi+2pik
t2=(9-1)/(-10)=-0.8; sinx=-0.8; x=-arcsin0.8+2pik

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