aCosA + bSinA =m and aSinA - bCosA =n prove that a2+b2= m2+n2

1.	aCosA + bSinA =m and aSinA - bCosA =n prove that a2+b2= m2+n2
Answer» m2+n2=(acos+bcos)^2+(asin-bcos)^2 =a2cos2+a2sin2+2absincos+a2sin2+b2cos2 - 2absincos =a2(cos2+sin2)+b2(cos2+sin2) =a2(1)+b2(1) =a2+b2

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