Take the slope of the straight line passing through the point (0,4) as t, and write the elliptic equation x square ratio 4 plus y square ratio 16 equal to 1 in the form of parametric equation with t as the parameter!

Take the slope of the straight line passing through the point (0,4) as t, and write the elliptic equation x square ratio 4 plus y square ratio 16 equal to 1 in the form of parametric equation with t as the parameter!

Let P (x, y) m (0,4) be a point on an ellipse
Then PM equation y = TX + 4
Substituting into the elliptic equation x ^ 2 / 4 + (TX + 4) ^ 2 / 16 = 1
The results show that x [(4 + T ^ 2) x + 8t] = 0
Parameter equation {x = - 8t / (4 + T ^ 2) y = = (16-4t ^ 2) / (4 + T ^ 2)
In addition, x = 0, y = - 4 can not be expressed, so it needs to be supplemented