If (a+b)=0,than sin (a_b) can be reduced to

1.	If (a+b)=0,than sin (a_b) can be reduced to
Answer» It should be cos(a+b)=0then, cos(a+b)=cos90°=>a+b=90°=>a=90°-bNowsin(a-b)=sin(90-b-b)=sin(90-2b)=cos2b [as sin(90-x)=cosx]

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