X2 t03 01 ellipse (2012)
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X2 t03 01 ellipse (2012)

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X2 t03 01 ellipse (2012) X2 t03 01 ellipse (2012) Presentation Transcript

  • Conics
  • ConicsThe locus of points whose distance from a fixed point (focus) is amultiple, e, (eccentricity) of its distance from a fixed line (directrix)
  • ConicsThe locus of points whose distance from a fixed point (focus) is amultiple, e, (eccentricity) of its distance from a fixed line (directrix)
  • 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
  • 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
  • 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
  • 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
  • Ellipse (e < 1) y bA’ A-a a x -b
  • Ellipse (e < 1) y bA’ A-a S a Z x -b
  • Ellipse (e < 1) y b A’ A -a S a Z x -bSA = eAZ and SA’ = eA’Z
  • 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)
  • 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
  • b A’ A -a S a Z x -b(1) + (2); 2SA’ = 2a(1 + e) SA’ = a(1 + e)
  • 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)
  • 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
  • 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 
  • 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 
  • 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 
  • 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
  • S ae,0  b PP  x, y  N A’ A -a aN , y a S Z x   e  -b
  • S ae,0  b PP  x, y  N A’ A -a aN , y a S Z x   e  -b SP  ePN
  • 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
  • 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 
  • 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
  • b2when x  0, y  b 1 a 1  e  i.e. 2 2 b 2  a 2 1  e 2 
  • 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
  • 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
  • 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
  • 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.
  • 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
  • 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
  • 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
  • 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
  • y Auxiliary circle-3 3 x
  • b 5 y a  3    Auxiliary circle-3 3 x
  • b 5 y a  3    Auxiliary circle 5-3 3 x  5
  • b 5 y a  3    Auxiliary circle 5-3 3 x  5
  • b 5 y a  3    Auxiliary circle 5-3 3 x  5
  • b 5 y a  3    Auxiliary circle 5-3 3 x  5
  • b 5 y a  3    Auxiliary circle 5-3 3 x  5
  • b 5 y a  3    Auxiliary circle 5-3 3 x  5
  • b 5 y a  3    Auxiliary circle 5-3 3 x  5
  • b 5 y a  3    Auxiliary circle 5-3 S’(-2,0) S(2,0) 3 x  5
  • b 5 y a  3    Auxiliary circle 5 -3 S’(-2,0) S(2,0) 3 x  5 9 9x x 2 2
  • 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
  • (ii) 9 x 2  4 y 2  18 x  16 y  11  0
  • (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
  • (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
  • (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
  • (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)
  • (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
  • (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
  • (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
  • (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