The sides of the ABC triangle has the following set of vertices: {(1,3), (3,1), (4,3)}
The A'B'C' triangle has the following set of vertices: {(2,6),(6,2),(8,6)}
We can check that AB = 2sqrt(2), BC = sqrt(5) and CA = 3, while A'B' = 4sqrt(2), B'C' = 2sqrt(5) and C'A' = 6
Therefore, scale factor of dilation of the triangle is 1/2.