See the video for the description of a sun reflector/concentrator.
Create a program that will create (draw/plot) the cross section the maximally efficient curve for circle (pipe) of a given size.
Let the user specify the allowed incoming angle as specified in the video. (10° to 40° ?)
Let the user specify the 2D size of an imaginary box the reflector/concentrator curve will fit in. The box is used to limit the maximum width or height the reflector/concentrator will be. (Inches, feet, ... ?)
Note:
DIY Solar Concentrators, Made Better. (YouTube)