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sin((5pi)/18)-cos((4pi)/9)=sqrt(3)sin(pi...

`sin((5pi)/18)-cos((4pi)/9)=sqrt(3)sin(pi/9)`

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We have to proof,
`sin((5pi)/18)-cos((4pi)/9)=sqrt(3)sin(pi/9)`
Let,
L.H.S=`sin((5pi)/18)-cos((4pi)/9)`
L.H.S.=`sin((5pi)/18)-cos(((pi)/2)-((pi)/18))`
L.H.S.=`sin((5pi)/18)-sin(((pi)/18))`
As we know the formula,
`sin(A)-sin(B)= 2[sin(((A) -(B))/2)cos(((A)+(B))/2)]`
then, ...
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