# Conic Sections in Polar Coordinates Lesson 10.6. 2 Definition of Parabola Set of points equal distance from a point and a line  Point is the focus 

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Conic Sections in Polar Coordinates Lesson 10.6

2 Definition of Parabola Set of points equal distance from a point and a line  Point is the focus  Line is the directrix If the ratio of the two distances is different from 1, other curves result

3 General Definition of a Conic Section Given a fixed line L and a fixed point F A conic section is the set of all points P in the plane such that F L d(P, F) d(P, L) Note: This e stands for eccentricity. It is not the same as e = 2.71828 Note: This e stands for eccentricity. It is not the same as e = 2.71828

4 General Definition of a Conic Section When e has different values, different curves result 0 < e < 1The conic is an ellipse e = 1The conic is a parabola e > 1The conic is a hyperbola Note: The distances are positive  e is always greater than zero

5 Polar equations of Conic Sections A polar equation that has one of the following forms is a conic section When cos is used, major axis horizontal  Directrix at y = p When sin is used, major axis vertical  Directrix at x = p

6 Example Given Identify the conic  What is the eccentricity?  e = ______ Graph the conic Note the false asymptotes

7 Special Situation Consider  Eccentricity = ?  Conic = ? Now graph Note it is rotated by -π/6

8 Finding the Polar Equation Given directrix y = -5 and e = 1  What is the conic? Which equation to use? 5 1 y = - 5

9 Assignment Lesson 10.6 Page 438 Exercises 1 – 19 odd

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