Stephen ARNOLD
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A4 Paper Folding

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  1. Drag the point P to find the height value for which the area of the triangle is greatest.

  2. Build an algebraic model for the area of the triangle by defining the following functions:

      height(x) =
      hypot(x) =
      base(x) =
      myarea(x) =

  3. Using Calculus build the derivative function for myarea(x) and use this to find the exact value of the height for which the area of the triangle is greatest:

      myderiv(x) =
      myderiv(x) = 0 when x =


Peter Fox and Steve Arnold. Thanks to Mike May S.J. for his JavaScripting. 24/03/2008, Created with GeoGebra


This problem may also be modelled using CabriJr on the TI-83/84 series calculator. Click on the graphic below to download the file and try it yourself!

Try having students work in pairs: one generating data points using the CabriJr model and the partner entering these into lists to plot and then to help build their algebraic model!



And just wait until you try this with TI-nspire CAS!

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