(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The original problem:

[tex]z=\sqrt{(x1-x)^2+(y1-y)^2}+\sqrt{(x2-x)^2+(y2-y)^2}[/tex]

Given that: ax+by+c=0, Find the minimum possible value of z.

x1,y1,x2,y2,a,b and c are constants.

3. The attempt at a solution

I think I need to apply the partial derivative. I would get a relation in x and y. I have a second relation in x and y which might simultaneously solve.

But my concepts of partial derivative seem shaky. I don't know how to find the least value of a function which is dependent on 2 variables. I tried going through the articles given in wikipedia and wolfram(Mathworld) but they dont talk about the minimum value of such a function. I would also like to draw your attention to my previous post:

https://www.physicsforums.com/showthread.php?t=262715

I hope someone will help me understand this!!

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# Homework Help: Partial Derivatives

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