Solve 2nd Order ODE Mirror for Parallel Reflection from Origin

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Homework Help Overview

The problem involves finding the equation of a curved mirror that reflects light rays emanating from the origin parallel to the x-axis. This is framed within the context of second-order ordinary differential equations (ODEs).

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the geometric properties of the mirror and the relationships between the tangent line, the line from the origin, and the conditions for reflection. Questions arise about deriving the necessary equations and how to formulate them into an ODE.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the relationships between the equations involved and how to proceed from the established geometric conditions to formulating an ODE. Some participants express understanding of certain aspects while still grappling with the overall formulation.

Contextual Notes

There is a noted lack of clarity on how to connect the geometric relationships to the creation of an ODE, and participants are exploring the implications of equal angles in the context of reflection.

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Homework Statement


A curved mirror of equation y=y(x) has that property that whenever a ray of light emanates from the origin it reflects parallel to the x-axis. Find the equation of the mirror


Don't even know how to get started on this, Don't need a solution just need some starting hints / help!

thank you
 
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Let y= f(x) be the equation of the mirror. At point (x_0, f(x_0)), the tangent line to the curve is given by y= f&#039;(x_0)(x- x_0)+ f(x_0)[/tex]. The line parallel to the x-axis has equation y= f(x_0) and the equation of the line from the origin to the point on the curve has y= f(x_0)x/x_0.<br /> <br /> To &quot;reflect from the mirror&quot; those two lines must make equal angles with the tangent line.
 
HallsofIvy said:
Let y= f(x) be the equation of the mirror. At point (x_0, f(x_0)), the tangent line to the curve is given by y= f&#039;(x_0)(x- x_0)+ f(x_0)[/tex]. The line parallel to the x-axis has equation y= f(x_0) and the equation of the line from the origin to the point on the curve has y= f(x_0)x/x_0.<br /> <br /> To &quot;reflect from the mirror&quot; those two lines must make equal angles with the tangent line.
<br /> <br /> How do I come up with this information my self and how do you know the the origin to the point on the curve has equation y= f(x_0)x/x_0?
 
Bump!, I understand how you got the equation at the point to the curve now.
I don't understand how to use these three equations to make an ODE. I know that the angles must be equal but I don't understand how they relate to the question. I also know I can take a tangent line at the origin, to the intersection of y = y= f(x_0) and that would be a equation that has the same slope has my tangent line at x_0
 
bump! same question still
 

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