Let a belong to (0, π / 2), and the equation x ^ 2 / Sina + y ^ 2 / cosa = 1 denotes an ellipse with focus on the x-axis, then a belongs to

Let a belong to (0, π / 2), and the equation x ^ 2 / Sina + y ^ 2 / cosa = 1 denotes an ellipse with focus on the x-axis, then a belongs to

A belongs to (0, π / 2), and the equation x ^ 2 / Sina + y ^ 2 / cosa = 1 represents the ellipse with the focus on the X axis
So Sina > cosa solution gives that a belongs to (π / 4, π / 2)