1. Explain how eccentricity determines which conic section is given.
2. If a conic section is written as a polar equation, what must be true of the denominator?
3. If a conic section is written as a polar equation, and the denominator involves sin θsin θ, what conclusion can be drawn about the directrix?
4. If the directrix of a conic section is perpendicular to the polar axis, what do we know about the equation of the graph?
5. What do we know about the focus/foci of a conic section if it is written as a polar equation?
For the following exercises, identify the conic with a focus at the origin, and then give the directrix and eccentricity.
6. r=61−2 cos θr=61−2 cos θ
7. r=34−4 sin θr=34−4 sin θ
8. r=84−3 cos θr=84−3 cos θ
9. r=51+2 sin θr=51+2 sin θ
10. r=164+3 cos θr=164+3 cos θ
11. r=310+10 cos θr=310+10 cos θ
12. r=21−cos θr=21−cos θ
13. r=47+2 cos θr=47+2 cos θ
14. r(1−cos θ)=3r(1−cos θ)=3
15. r(3+5sin θ)=11r(3+5sin θ)=11
16. r(4−5sin θ)=1r(4−5sin θ)=1
17. r(7+8cos θ)=7r(7+8cos θ)=7
For the following exercises, convert the polar equation of a conic section to a rectangular equation.
18. r=41+3 sin θr=41+3 sin θ
19. r=25−3 sin θr=25−3 sin θ
20. r=83−2 cos θr=83−2 cos θ
21. r=32+5 cos θr=32+5 cos θ
22. r=42+2 sin θr=42+2 sin θ
23. r=38−8 cos θr=38−8 cos θ
24. r=26+7 cos θr=26+7 cos θ
25. r=55−11 sin θr=55−11 sin θ
26. r(5+2 cos θ)=6r(5+2 cos θ)=6
27. r(2−cos θ)=1r(2−cos θ)=1
28. r(2.5−2.5 sin θ)=5r(2.5−2.5 sin θ)=5
29. r=6sec θ−2+3 sec θr=6sec θ−2+3 sec θ
30. r=6csc θ3+2 csc θr=6csc θ3+2 csc θ
For the following exercises, graph the given conic section. If it is a parabola, label the vertex, focus, and directrix. If it is an ellipse, label the vertices and foci. If it is a hyperbola, label the vertices and foci.
31. r=52+cos θr=52+cos θ
32. r=23+3 sin θr=23+3 sin θ
33. r=105−4 sin θr=105−4 sin θ
34. r=31+2 cos θr=31+2 cos θ
35. r=84−5 cos θr=84−5 cos θ
36. r=34−4 cos θ
37. r=21−sin θ
38. r=63+2 sin θ
39. r(1+cos θ)=5
40. r(3−4sin θ)=9
41. r(3−2sin θ)=6
42. r(6−4cos θ)=5
For the following exercises, find the polar equation of the conic with focus at the origin and the given eccentricity and directrix.
43. Directrix: x=4;e=15
44. Directrix: x=−4;e=5
45. Directrix: y=2;e=2
46. Directrix: y=−2;e=12
47. Directrix: x=1;e=1
48. Directrix: x=−1;e=1
49. Directrix: x=−14;e=72
50. Directrix: y=25;e=72
51. Directrix: y=4;e=32
52. Directrix: x=−2;e=83
53. Directrix: x=−5;e=34
54. Directrix: y=2;e=2.5
55. Directrix: x=−3;e=13
Equations of conics with an xy term have rotated graphs. For the following exercises, express each equation in polar form with r as a function of θ.
56. xy=2
57. x2+xy+y2=4
58. 2x2+4xy+2y2=9
59. 16x2+24xy+9y2=4
60. 2xy+y=1
Candela Citations
- Precalculus. Authored by: OpenStax College. Provided by: OpenStax. Located at: http://cnx.org/contents/fd53eae1-fa23-47c7-bb1b-972349835c3c@5.175:1/Preface. License: CC BY: Attribution