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Nov 12th, 2019
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  1. y = ax^2 + bx + c with x as time and y as vertical displacement
  2.  
  3. one root is (0,0), other is (duration,0)
  4.  
  5. y = ax^2 + bx is valid bc there will never be a y intercept
  6.  
  7. rules for simplifying quadratics:
  8. if (x+q)(x+g):
  9.  
  10. b = q + g
  11. c = q * g
  12.  
  13. for our case:
  14.  
  15. b = q + g
  16. 0 = q * g <-- either q or g has to be zero, it will be q in this case bc we want leftmost root to be origin.
  17.  
  18. (x+0) (x+duration)
  19.  
  20. so the vertex of the point is given by: (duration/2, maxVert)
  21.  
  22. however, vertex is found by:
  23.  
  24. vertex = -b/2a
  25.  
  26. therefore:
  27. duration = d for simplification.
  28.  
  29. d/2 = -b/2a
  30.  
  31. factor in previous b:
  32.  
  33. d/2 = -(q + g)/2a
  34.  
  35. we know q = 0 and g = duration:
  36.  
  37. d/2 = -d/2a
  38.  
  39. solve for a:
  40.  
  41. multiply by 2a:
  42.  
  43. 2ad/2 = -d
  44.  
  45. reduce:
  46.  
  47. ad = -d
  48.  
  49. divide by d:
  50.  
  51. a = -d/d
  52.  
  53. a = -1
  54.  
  55.  
  56. factor our newly discovered variables into our original function:
  57.  
  58. y = -1x^2 + (q + g)x + c
  59.  
  60. reduce:
  61.  
  62. y = -x^2 + (d)x
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