Question 1136234

(sin3A + sinA)sinA + (cosA - cosA)cosA = 0->need correction-> (cosA - cosA)cosA should be (cos3A - cosA)cosA


{{{(sin(3 A) + sin(A))sin(A )+ (cos(3 A) - cos(A))cos(A )= 0}}} 

{{{(sin(3 A) + sinA)sin(A) + (cos(3 A) - cosA)cos(A) = 0 }}}

{{{sin(3 A)*sinA  + sin^2(A)+ cos(3 A)*cos(A)-cos^2(A)=0}}}

{{{sin^2(A) (2 cos(2 A) + 1)+ (sin^2(A)-cos^2(A))+cos^2(A) (2 cos(2 A) - 1)=0}}}....since {{{(sin^2(A)-cos^2(A))=-cos(2 A)}}} we have

{{{sin^2(A) (2 cos(2 A) + 1)-cos(2 A)+cos^2(A) (2 cos(2 A) - 1)=0}}}

{{{sin^2(A)*2 cos(2 A) + sin^2(A)-cos(2 A)+cos^2(A)*2 cos(2 A) - cos^2(A)=0}}}

{{{(sin^2(A)*2 cos(2 A) -cos(2 A)+cos^2(A)*2 cos(2 A))+ (sin^2(A) - cos^2(A))=0}}}

{{{(2sin^2(A) -1+2cos^2(A)) cos(2 A)-cos(2 A)=0}}}

{{{(2(sin^2(A) +cos^2(A))-1) cos(2 A)-cos(2 A)=0}}}

{{{(2*1-1) cos(2 A)-cos(2 A)=0}}}

{{{cos(2 A)-cos(2 A)=0}}}

{{{0=0}}}