2Sin ^ 2x + cos ^ 2Y = 1, find the value range of sin ^ 2x + cos ^ 2Y

2Sin ^ 2x + cos ^ 2Y = 1, find the value range of sin ^ 2x + cos ^ 2Y

2sin^2x+cos^2y=1
cos^2y=1-2sin^2x≥0
∴0≤1-2sin^2x≤1
∴0≤sin^2x≤1/2
∴sin^2x+cos^2y=sin^2x+1-2sin^2x=1-sin^2x
∵0≤sin^2x≤1/2
∴1/2≤1-sin^2x≤1
∴1/2≤sin^2x+cos^2y≤1