Navigation Panel: 

  Go backward to This is Not the Fallacy
  Go up to A Ladder Will Fall Infinitely Fast when Pulled
  Go forward to This is Not the Fallacy
  Switch to graphical version (better pictures & formulas)
  Go to University of Toronto Mathematics Network Home Page

This step is not the source of the fallacy.

This step follows from the previous step (y = sqrt(L^2 - x^2)) by differentiating this expression (using the chain rule and the formula for the derivative of the square root function), and doing a little simplification.
Why don't you go back to the list of steps in the proof and see if you can identify which one is wrong, now that you know it isn't this one?
This page last updated: May 26, 1998
Original Web Site Creator / Mathematical Content Developer: Philip Spencer
Current Network Coordinator and Contact Person: Joel Chan -

Navigation Panel: Previous | Up | Forward | Graphical Version | U of T Math Network Home