Comments on: Elliptical carrom board

By: Rithwik K

Rithwik K — Tue, 31 Mar 2009 07:10:36 +0000

The other focus

An ellipse is the locus of all points for which the sum of distances from two(given) focii are the same

By: p vs np

p vs np — Tue, 31 Mar 2009 06:30:17 +0000

@Yaksha
Lol! :D

By: Ajay Parasuram

Ajay Parasuram — Mon, 30 Mar 2009 23:30:47 +0000

The striker will pass through either one of the 2 foci (+/-ae,0)

By: MGS

MGS — Mon, 30 Mar 2009 19:50:35 +0000

it passes thru the other focal point.

Because: Reflection Theory. Angle of Incidence = Angle of Reflection.

http://cage.rug.ac.be/~hs/billiards/billiards.html

By: p vs np

p vs np — Mon, 30 Mar 2009 19:06:05 +0000

Aaw.. The striker shall pass through the other focus of the carrom board/ellipse.

This is so, because the normal at the point of intersection of the lines passing through the two focii on the perimeter of the curve, is the angular bisector of the angle formed. Hence, by rules of ideal reflectivity (incidence angle= reflected angle), it needs to pass through the other focus.

By: sand

sand — Mon, 30 Mar 2009 19:02:56 +0000

Through the other focus…. its like reflection, optical elliptical mirrors (convex and concave) are constructed by this principle.

By: shrik

shrik — Mon, 30 Mar 2009 18:40:44 +0000

Through the other focus! This is the principle of whisper chambers and elliptical mirrors. Not sure what the property itself would be called though…

*google* *google*

The tangent line always makes equal angles with the generator lines? If the inside of an ellipse is a mirror, a light ray leaving one focus will always pass through the other? Actually by definition, since the distance between the rebound point and the foci always remains constant, one could say that it’s not any property, but the very definition of an ellipse that explains this.

By: Ananth

Ananth — Mon, 30 Mar 2009 17:13:21 +0000

The reflective property of an ellipse. An ellipse has 2 focal points. The striker will definitely go through the other focal point in the ellipse.

By: Poornima

Poornima — Mon, 30 Mar 2009 16:41:52 +0000

The other focus?
Is it because, the sum of distances from any point on the ellipse to the foci is equal?

By: Neeraj

Neeraj — Mon, 30 Mar 2009 15:37:53 +0000

The striker will surely pass through the other focus of the ellipse and the property is the reflection property of the ellipse.