If you look at the reduced triangle, the height is 2. Therefore you would have to multiply by 4 instead of 0.4 even if the scale factor is 0.4. The reason is, you are enlarging the triangle to find the bigger triangle. If you did 0.4 times 2 you would get 0.8. But that wouldn’t make any sense if you said that that was the height of the ENLARGED triangle.
