Section Exercises

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 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=612 cos θ

7. r=344 sin θ

8. r=843 cos θ

9. r=51+2 sin θ

10. r=164+3 cos θ

11. r=310+10 cos θ

12. r=21cos θ

13. r=47+2 cos θ

14. r(1cos θ)=3

15. r(3+5sin θ)=11

16. r(45sin θ)=1

17. r(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 θ

19. r=253 sin θ

20. r=832 cos θ

21. r=32+5 cos θ

22. r=42+2 sin θ

23. r=388 cos θ

24. r=26+7 cos θ

25. r=5511 sin θ

26. r(5+2 cos θ)=6

27. r(2cos θ)=1

28. r(2.52.5 sin θ)=5

29. r=6sec θ2+3 sec θ

30. r=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 θ

32. r=23+3 sin θ

33. r=1054 sin θ

34. r=31+2 cos θ

35. r=845 cos θ

36. r=344 cos θ

37. r=21sin θ

38. r=63+2 sin θ

39. r(1+cos θ)=5

40. r(34sin θ)=9

41. r(32sin θ)=6

42. r(64cos 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