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Math 1/2

Lesson 4

Rabbit Run

Maximize area with a fixed perimeter using a quadratic model.

Learning Focus

Model area with a fixed perimeter and identify vertex / maximum features of a quadratic.

Big idea

With 72 ft of fencing for a rectangle, if one side is xx, the adjacent side is 36−x36-x (because 2x+2w=722x+2w=72).

Area: A(x)=x(36−x)=36x−x2A(x)=x(36-x)=36x-x^2.

Maximum area occurs at the vertex of this downward parabola.

Takeaways

  • Not all quadratics are discrete figure patterns — some are continuous area models.
  • Vertex form / symmetry helps find max/min.