Lesson #152 Ellipses

  
Quote of the Day:
"Out of the public schools comes the greatness of the 
   nation."   -- Mark Twain

Objectives:
The student will analyze given ellipses.
The student will write the equation for an ellipse given
   certain information.


1. Definition of an Ellipse:
   An ellipse is the set of points in a plane whose
   distances from two fixed points have a constant sum.

       

2. Distribute a copy of the Ellipse paper to each 
   student.  Have each student trace out an ellipse while I 
   do one at the overhead.  The purpose of this is to have
   students understand the definition of the ellipse by 
   locating points which satisfy the definition.

        Ellipse Paper

3. Develop the equation for an ellipse with center at the 
   origin and major axis on the x-axis.

       
    Let the foci be (-c, 0) and (c, 0)
    Let the constant sum = 2a (the major axis)

       

        Click here for the full proof of the formula for the ellipse

4. The general forms for an ellipse are:

       

5. Examples:

       

6. Area of an Ellipse

7. Assignment:
   p. 761 (9a, 10a,b, 11b, 13a, 27a,b, 29b, 49)
   (Two-day assignment)
        Finish Ellipse Paper

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