Parabolic Envelope from Congruent Triangles
Requires a Wolfram Notebook System
Interact on desktop, mobile and cloud with the free Wolfram Player or other Wolfram Language products.
Consider a line and a point not on . Drag the orange point along . Draw a vertical line from . The perpendicular bisector of meets at a point that traces out a parabola and is tangent to the parabola. The focus and directrix of the parabola are and because is isoceles. The part of the vertical line m inside the parabola is the reflection in of the ray .
Contributed by: Harry Calkins (March 2011)
Open content licensed under CC BY-NC-SA
"Parabolic Envelope from Congruent Triangles"
Wolfram Demonstrations Project
Published: March 7 2011