The length of DC from the given figure is 3 units
Similarity theorem of triangles;
From the diagram shown, the ratio of the sides of the smaller triangle is equal to the larger triangle.
From the diagram;
Substitute the given sides into the formula;
12/9 = (12+4)/AD+DC
12/9 = 16/AD+DC
12/9 = 16/9+DC
Cross multiply
12(9+DC) = 9(16)
108 + 12DC = 144
12DC = 144 - 108
12DC = 36
DC = 36/12
DC = 3 units
Hence the length of DC is 3 units
Learn more on similar triangles here: https://brainly.com/question/2644832
