.50 retracement of the 829.20 high to the 823.60 low
(point a to point b) = 826.40
1.272 extension of the 826.20 high to the 824.50 low
(point c to point d) = 826.66
1.0 projection of the 823.60 low to the 826.20 high, projected from the
824.50 low (point b to point c, projected from point d) = 827.10
1.0 projection of the 826.20 low to the 829.20 high, projected from the
823.60 low (point x to point a, projected from point b) = 826.60