Question

cos^2x-7sinx+sinxcosx=7cosx

Answer 1

(cos(x)-7) (sin(x)+cos(x)) = 0
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1/2 (-14 sin(x)+sin(2 x)+cos(2 x)+1) = 7cos(x)
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1/2 (-14 sin(x)+sqrt(2) sin(2 x+pi/4)+1) = 7 cos(x)    
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x = 2 (pi n+tan^(-1)(1-sqrt(2))), n принадлежит Z
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x = 2 (pi n+tan^(-1)(1+sqrt(2))), n принадлежит Z  
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x = 2 pi n-cos^(-1)(7), n принадлежит Z
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x = 2 pi n+cos^(-1)(7), n принадлежит Z  
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