Author David Graser, Yavapai College, Prescott, AZ (


The two project letters below describe applications where students use the physical dimension of an arch to determine constants in the equation that models the hieght of the arch. In Project Letter 1, a catenary is used to model the St. Louis arch. In Project Letter 2, a parabola is used to model the height of the Rainbow Bridge in Arizona.

Each project can be used to explore function transformations with technology or how to solve for constants in a model equation.

  • Content Area – College Algebra, Precalculus
  • Time Frame – 2 to 3 weeks with mini-lectures
  • Published – November 29, 2009
  • Keywords – transformations

Project Content

Project Letter 1 (DOC | PDF)
Project Letter 2 (DOC | PDF)

Scaffolding Resources



  • You can have the students experiment with the values of the constants on a graphing calculator. Another approach is to take the physical dimensions and substitue them into the model equation. The resulting equations can be used to solve for the unknown constants and then checked on a graphing calculator.

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