X2 T03 01 ellipse (2011)

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X2 T03 01 ellipse (2011)

  1. 1. Conics
  2. 2. ConicsThe locus of points whose distance from a fixed point (focus) is amultiple, e, (eccentricity) of its distance from a fixed line (directrix)
  3. 3. ConicsThe locus of points whose distance from a fixed point (focus) is amultiple, e, (eccentricity) of its distance from a fixed line (directrix)
  4. 4. ConicsThe locus of points whose distance from a fixed point (focus) is amultiple, e, (eccentricity) of its distance from a fixed line (directrix) e=0 circle
  5. 5. ConicsThe locus of points whose distance from a fixed point (focus) is amultiple, e, (eccentricity) of its distance from a fixed line (directrix) e=0 circle e<1 ellipse
  6. 6. ConicsThe locus of points whose distance from a fixed point (focus) is amultiple, e, (eccentricity) of its distance from a fixed line (directrix) e=0 circle e<1 ellipse e=1 parabola
  7. 7. ConicsThe locus of points whose distance from a fixed point (focus) is amultiple, e, (eccentricity) of its distance from a fixed line (directrix) e=0 circle e<1 ellipse e=1 parabola e>1 hyperbola
  8. 8. Ellipse (e < 1) y bA’ A-a a x -b
  9. 9. Ellipse (e < 1) y bA’ A-a S a Z x -b
  10. 10. Ellipse (e < 1) y b A’ A -a S a Z x -bSA = eAZ and SA’ = eA’Z
  11. 11. Ellipse (e < 1) y b A’ A -a S a Z x -b SA = eAZ and SA’ = eA’Z(1) SA’ + SA = 2a(2) SA’ – SA = e(A’Z – AZ)
  12. 12. Ellipse (e < 1) y b A’ A -a S a Z x -b SA = eAZ and SA’ = eA’Z(1) SA’ + SA = 2a(2) SA’ – SA = e(A’Z – AZ) = e(AA’) = e(2a) = 2ae
  13. 13. b A’ A -a S a Z x -b(1) + (2); 2SA’ = 2a(1 + e) SA’ = a(1 + e)
  14. 14. b A’ A -a S a Z x -b(1) + (2); 2SA’ = 2a(1 + e) (1) - (2); 2SA = 2a(1 - e) SA’ = a(1 + e) SA = a(1 - e)
  15. 15. b A’ A -a S a Z x -b (1) + (2); 2SA’ = 2a(1 + e) (1) - (2); 2SA = 2a(1 - e) SA’ = a(1 + e) SA = a(1 - e)FocusOS = OA - SA
  16. 16. b A’ A -a S a Z x -b (1) + (2); 2SA’ = 2a(1 + e) (1) - (2); 2SA = 2a(1 - e) SA’ = a(1 + e) SA = a(1 - e)FocusOS = OA - SA = a – a(1 – e) = ae S  ae,0 
  17. 17. b A’ A -a S a Z x -b (1) + (2); 2SA’ = 2a(1 + e) (1) - (2); 2SA = 2a(1 - e) SA’ = a(1 + e) SA = a(1 - e)Focus DirectrixOS = OA - SA OZ = OA + AZ = a – a(1 – e) = ae S  ae,0 
  18. 18. b A’ A -a S a Z x -b (1) + (2); 2SA’ = 2a(1 + e) (1) - (2); 2SA = 2a(1 - e) SA’ = a(1 + e) SA = a(1 - e)Focus DirectrixOS = OA - SA OZ = OA + AZ SA = a – a(1 – e)  OA   SA  eAZ  = ae e S  ae,0 
  19. 19. b A’ A -a S a Z x -b (1) + (2); 2SA’ = 2a(1 + e) (1) - (2); 2SA = 2a(1 - e) SA’ = a(1 + e) SA = a(1 - e)Focus DirectrixOS = OA - SA OZ = OA + AZ SA = a – a(1 – e)  OA   SA  eAZ  = ae e ae a1  e  S  ae,0    e e a a  directrices x    e e
  20. 20. S ae,0  b PP  x, y  N A’ A -a aN , y a S Z x   e  -b
  21. 21. S ae,0  b PP  x, y  N A’ A -a aN , y a S Z x   e  -b SP  ePN
  22. 22. S ae,0  b PP  x, y  N A’ A -a aN , y a S Z x   e  -b SP  ePN 2 x  ae 2   y  02  e  x     y  y 2 a    e 2 2 a  x  ae   y  e  x   2 2  e
  23. 23. S ae,0  b P P  x, y  N A’ A -a a N , y a S Z x   e  -b SP  ePN 2  x  ae 2   y  02  e  x     y  y 2 a    e 2 2 a  x  ae   y  e  x   2 2  ex 2  2aex  a 2 e 2  y 2  e 2 x 2  2aex  a 2 x 2 1  e 2   y 2  a 2 1  e 2 
  24. 24. S ae,0  b P P  x, y  N A’ A -a a N , y a S Z x   e  -b SP  ePN 2  x  ae 2   y  02  e  x     y  y 2 a    e 2 2 a  x  ae   y  e  x   2 2  ex 2  2aex  a 2 e 2  y 2  e 2 x 2  2aex  a 2 x 2 1  e 2   y 2  a 2 1  e 2  x2 y2  2 1 a a 1  e  2 2
  25. 25. b2when x  0, y  b 1 a 1  e  i.e. 2 2 b 2  a 2 1  e 2 
  26. 26. b2when x  0, y  b 1 a 1  e  i.e. 2 2 b 2  a 2 1  e 2  Ellipse: (a > b) x2 y2 2  2 1 a b where; b 2  a 2 1  e 2  focus :  ae,0  a directrices : x   e e is the eccentricity major semi-axis = a units minor semi-axis = b units
  27. 27. b2when x  0, y  b 1 a 1  e  i.e. 2 2 b 2  a 2 1  e 2  Ellipse: (a > b) x2 y2 Note: If b > a 2  2 1 a b foci on the y axis where; b  a 1  e 2 2 2  a 2  b 2 1  e 2  focus :  ae,0  focus : 0,be  a b directrices : x   directrices : y   e e e is the eccentricity major semi-axis = a units minor semi-axis = b units
  28. 28. b2when x  0, y  b 1 a 1  e  i.e. 2 2 b 2  a 2 1  e 2  Ellipse: (a > b) x2 y2 Note: If b > a 2  2 1 a b foci on the y axis where; b  a 1  e 2 2 2  a 2  b 2 1  e 2  focus :  ae,0  focus : 0,be  a b directrices : x   directrices : y   e e e is the eccentricity major semi-axis = a units Area  ab minor semi-axis = b units
  29. 29. e.g. Find the eccentricity, foci and directrices of the ellipse x2 y2   1 and sketch the ellipse showing all of the important 9 5 features.
  30. 30. e.g. Find the eccentricity, foci and directrices of the ellipse x2 y2   1 and sketch the ellipse showing all of the important 9 5 features. x2 y2  1 9 5 a2  9 a3
  31. 31. e.g. Find the eccentricity, foci and directrices of the ellipse x2 y2   1 and sketch the ellipse showing all of the important 9 5 features. x2 y2  1 b2  5 9 5 a 2 1  e 2   5 a2  9 a3
  32. 32. e.g. Find the eccentricity, foci and directrices of the ellipse x2 y2   1 and sketch the ellipse showing all of the important 9 5 features. x2 y2  1 b2  5 9 5 a 2 1  e 2   5 91  e 2   5 a2  9 a3 5 1 e 2 9 4 e  2 9 2 e 3
  33. 33. e.g. Find the eccentricity, foci and directrices of the ellipse x2 y2   1 and sketch the ellipse showing all of the important 9 5 features. x2 y2  1 b2  5 9 5 a 2 1  e 2   5 91  e 2   5 a2  9 2 a3  eccentricity  5 3 1 e 2 9 foci :  2,0  4 e  2 3 9 directrices : x  3  2 2 e 9 3 x 2
  34. 34. y Auxiliary circle-3 3 x
  35. 35. b 5 y a  3    Auxiliary circle-3 3 x
  36. 36. b 5 y a  3    Auxiliary circle 5-3 3 x  5
  37. 37. b 5 y a  3    Auxiliary circle 5-3 3 x  5
  38. 38. b 5 y a  3    Auxiliary circle 5-3 3 x  5
  39. 39. b 5 y a  3    Auxiliary circle 5-3 3 x  5
  40. 40. b 5 y a  3    Auxiliary circle 5-3 3 x  5
  41. 41. b 5 y a  3    Auxiliary circle 5-3 3 x  5
  42. 42. b 5 y a  3    Auxiliary circle 5-3 3 x  5
  43. 43. b 5 y a  3    Auxiliary circle 5-3 S’(-2,0) S(2,0) 3 x  5
  44. 44. b 5 y a  3    Auxiliary circle 5 -3 S’(-2,0) S(2,0) 3 x  5 9 9x x 2 2
  45. 45. b 5 y a  3    Auxiliary circle 5 -3 S’(-2,0) S(2,0) 3 x  5 9 9 x x 2 2Major axis = 6 units Minor axis  2 5 units
  46. 46. (ii) 9 x 2  4 y 2  18 x  16 y  11  0
  47. 47. (ii) 9 x 2  4 y 2  18 x  16 y  11  0 x 2  2 x y 2  4 y 11   4 9 36
  48. 48. (ii) 9 x 2  4 y 2  18 x  16 y  11  0 x 2  2 x y 2  4 y 11   4 9 36  x  12  y  22 11 1 4     4 9 36 4 9
  49. 49. (ii) 9 x 2  4 y 2  18 x  16 y  11  0 x 2  2 x y 2  4 y 11   4 9 36  x  12  y  22 11 1 4     4 9 36 4 9  x  12  y  22  1 4 9
  50. 50. (ii) 9 x 2  4 y 2  18 x  16 y  11  0 x 2  2 x y 2  4 y 11   4 9 36  x  12  y  22 11 1 4     4 9 36 4 9  x  12  y  22  1 4 9 centre : (1,2)
  51. 51. (ii) 9 x 2  4 y 2  18 x  16 y  11  0 x 2  2 x y 2  4 y 11   4 9 36  x  12  y  22 11 1 4     4 9 36 4 9  x  12  y  22  1 4 9 centre : (1,2) b2  9 b3
  52. 52. (ii) 9 x 2  4 y 2  18 x  16 y  11  0 x 2  2 x y 2  4 y 11   4 9 36  x  12  y  22 11 1 4     4 9 36 4 9  x  12  y  22  1 4 9 centre : (1,2) b2  9 a 2  b 2 1  e 2  b3 4  91  e 2  5 e 3
  53. 53. (ii) 9 x 2  4 y 2  18 x  16 y  11  0 x 2  2 x y 2  4 y 11   4 9 36  x  12  y  22 11 1 4     4 9 36 4 9  x  12  y  22  1 4 9 centre : (1,2) b2  9 a 2  b 2 1  e 2  b3 4  91  e 2  5 e 3 foci :  1,2  5  9 directrices : y  2  5
  54. 54. (ii) 9 x 2  4 y 2  18 x  16 y  11  0 x 2  2 x y 2  4 y 11   4 9 36  x  12  y  22 11 1 4     4 9 36 4 9  x  12  y  22 Exercise 6A; 1, 2, 3, 5, 7,  1 4 9 8, 9, 11, 13, 15 centre : (1,2) b2  9 a 2  b 2 1  e 2  b3 4  91  e 2  5 e 3 foci :  1,2  5  9 directrices : y  2  5

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