如何在给定边界矩形的情况下找到椭圆长轴的旋转角度？

I have an ellipse centered at (0,0) and the bounding rectangle is x = [-5,5], y = [-6,6]. The ellipse intersects the rectangle at (-5,3),(-2.5,6),(2.5,-6),and (5,-3)I have an ellipse centered at (0,0) and the bou