Need help with writing equation of an ellipse

Mathematics
Tutor: None Selected Time limit: 1 Day

Write the equation of an ellipse with one focus at the pole and vertices at the polar coordinates (3, pi) and (9, 2pi). 

I found the eccentricity (.66), but don't know where to go from here

May 10th, 2015

r =a(1-e^2)/{1-ecostheta)

theta = pi 

r = a(1-e) = 3

theta = 2pi 

r = a(1+e) = 9

solve for a and e 

(1-e)/(1+e) = 1/3

3-3e = 1+e 

 e=1/2 

a = 6

the equation is 

r = 18/4/(1-0.5*costheta)

=18/(4-2costheta) 

May 10th, 2015

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May 10th, 2015
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May 10th, 2015
Dec 7th, 2016
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