AB = B - A = [5, -1] - [-3, 2] = [8, -3]
|AB| = |[8, -3]| = √73
BC = k·[3, 8]
|BC| = |k·[3, 8]| = 35/√73 --> k = 35/73
BC = 35/73·[3, 8] = [105/73, 280/73]
C = B + BC = [5, -1] + [105/73, 280/73] = [470/73, 207/73] = [6.438, 2.836]
D = A + BC = [-3, 2] + [105/73, 280/73] = [- 114/73, 426/73] = [-1.562, 5.836]