Midpoint BC = [ (-9 + 1)/2 , (6 - 4) / 2 ] = [ -4, 1]
Midpoint AB = [ (5 -9)/2 , (4 + 6) / 2 ] = [ -2, 5]
Midpoint AC = [ (5 + 1) / 2 , (4 -4) / 2 ] = [ 3 , 0 ]
Slope AD = [ 4 - 1 ] / [ 5 - -4] = 1/3
Slope CE = [ -4-5] / [ 1 - -2] = -3
Slope BF = [ 6-0] / [ -9-3] = -1/2
Equation of line through AD
y = (1/3)(x + 4) + 1 (1)
Equation of line through CE
y = -3 ( x + 2) + 5 (2)
Equation of line through BF
y = (-1/2)(x -3) (3)
Set (1), (2) equal to find their x intersection
(1/3)(x + 4) + 1 = -3(x + 2) + 5
x + 4 + 3 = -9(x + 2) + 15
x+ 7 = -9x -18 + 15
x + 7 = -9x -3
10x = -10
x = -1
y = -3(-1+2) + 5 = 2
Intersection pt = ( -1 , 2)
Test in (3)
2 = (-1/2) (-1 -3)
2 = 2 true