“伸缩变换”是高中数学的选修内容,通过适当的变换可以把研究有关椭圆的问题转化为研究单位圆中的有关问题,大大减少计算量.椭圆x2/a2+y2/b2=1通过变换T:x′=x/a,y′=y/b可化为单位圆x′2+y′2=1.该变换具有如下的性质:性质1垂直于坐标轴的直线变换后仍然垂直于坐标轴,不垂直于坐标轴的直线的斜率变为原来的a/b倍. “Scaling ” is a high school mathematics elective, by the appropriate transformation can be related to the study of the elliptic problem into the study unit circle of the relevant issues, greatly reducing the computational complexity of the elliptic x2 / a2 + y2 / b2 = 1 by Transformation T: x ’= x / a, y’ = y / b can be transformed into the unit circle x’2 + y’2 = 1. The transformation has the following properties: Property 1 Vertical line perpendicular to the coordinate transformation is still vertical On axes, the slope of a line that is not perpendicular to the axis becomes the original a / b times.