Explanation:
angle bisector theorem :
the ratio of the 2 baseline segments is the same as the ratio of the 2 legs of the main triangle.
in our case :
44.8/56 = (x + 4)/35
x + 4 = 44.8×35/56 = 44.8×5/8 = 28 mm
x = 24
FYI : one way of explaining the theorem is : we could see this as 2 projections originating from E at the same angle but onto a tilted projection screen.
the length on the projection screen (HD or GD) is directly related to the distance from the projection point to the end of the tilted projection : ED or EG. and so the ratios of both projections must be equal (due to the equal angle).
so, in our case
35/56 = (x + 4)/44.8
which leads, of course, to the same result
44.8×35/56 = x + 4