Hi all,

I am stuck with the following question. This is a question posted to me by my physicist friend

Attached is the figure of a ellipse with a formula of

. In other word,

**it has a horizontal radius of 1.5 units** and vertical radius of 1 unit.

Now, suppose I

**launch a light from the coordinates (-1.5,0.0)** at an angle alpha

in such a way that the light will experience reflection on the surface. How am I going to find all the coordinates when the light hit the surface.

My approach is to find the derivative. Hence I got

. Then I extend the line until it hit the surface and I check the coordinates. Draw the tangent line and reflect it with protractor manually.

The process is rather tedious since extending the line is not really a rigorous proven way. I hope to hear whether is there any alternative better way of finding the coordinates

Thanks and hope for your help