If `x=Xcos theta-Ysin theta,y=Xsin theta+Ycos theta` and `x^2+4x y+y^2=A X^2+B Y^2, 0lt=thetalt=pi/2` then

If quad X cos theta-Y sin theta,y=X sin theta+Y cos theta and x^(2)+4xy+y^(2)=AX^(2)+BY^(2)0<=theta<=(pi)/(2) then

If x = X cos theta- Y sin theta, y = X sin theta + Y cos theta and x^2 + 4 x y + y^2 = A X^2 + B Y^2 0 <= theta <= pi/2, then

If x=X cos theta- Y sin theta, y= X sin theta+ Y cos theta and x^(2)+4xy+y^(2)=AX^(2), B^(2),"for " 0 le theta le (pi)/(2) then (A,B)=

If x = X "cos" theta-Y "sin" theta, y = X "sin" theta + Y "cos" theta " and " x^(2) + 4xy + y^(2) =AX^(2) + BY^(2), 0 le theta le (pi)/(2), n in Z , then

Let 0 lt=thetalt=pi/2 and x=X cos theta+Y sin theta, y=X sin theta-Y cos theta such that x^2+2xy+y^2=aX^2+bY^2, where a and b are constant, then

Let 0 lt=thetalt=pi/2 and x=X cos theta+Y sin theta, y=X sin theta-Y cos theta such that x^2+2xy+y^2=aX^2+bY^2, where a and b are constant, then

Let 0 leq theta leq (pi)/(2) and x=X cos theta+Y sin theta y=X sin theta-Y cos theta such that x^(2)+4 x y+y^(2)=a X^(2)+b Y^(2) where a, b are constants, then

Let 0<=theta<=(pi)/(2) and x=X cos theta+Y sin theta,y=X sin theta-Y cos theta such that x^(2)+2xy+y^(2)=aX^(2)+bY^(2), where a and b are constant,then

If x= a(cos theta + sin theta ), y= a(sin theta + cos theta ), then [( d^2 y)/(d x^2 ) ] at theta = pi /4 ............. A) 0 B) 1 C) -1 D) 1/sqrt 2