" If "(sin alpha)/(a)=(cos alpha)/(b)," then "a sin2 alpha+b cos2 alpha=

I : If (cos alpha )/(a)=(sin alpha )/(b) then a cos 2 alpha + b cos 2 alpha =a II : If (sin alpha )/(a) =(cos alpha )/(b) then a sin 2 alpha + b cos 2 alpha = a

If (sin alpha )/(a) = ( cos alpha )/(b) , then a sin 2alpha + b cos 2 alpha =

IF tan alpha = ( sin alpha - cos alpha )/( sin alpha + cos alpha) , then sin alpha + cos alpha is

underset is If tan theta=(sin alpha-cos alpha)/(sin alpha+cos alpha), then sin alpha+cos alpha

If sin alpha + cos alpha = b, then sin 2 alpha is equal to

If (2sin alpha) / ({1 + cos alpha + sin alpha}) = y, then ({1-cos alpha + sin alpha}) / (1 + sin alpha) =

If (2sin alpha)/({1+cos alpha + sin alpha})=y, then ({1-cos alpha+sin alpha})/(1+sin alpha)=

If sin alpha + cos alpha = b then sin 2 alpha is equal to . . . . .