Answer:
10 cm
Explanation:
If we assume that DC is parallel to AB, then triangle DOC is similar to triangle AOB.
However, even with this assumption, there is not enough information in the diagram to solve for DO. We would also need to know the length of CO. Then we could write a proportion:
DO / (DO + 20) = CO / (CO + 24)
Edit: OD is 2 cm shorter than OC. If we call x the length of OD, then the length of OC is x+2.
Putting this into our proportion:
x / (x + 20) = (x + 2) / (x + 2 + 24)
x / (x + 20) = (x + 2) / (x + 26)
Cross multiply:
x (x + 26) = (x + 2) (x + 20)
Distribute:
x² + 26x = x² + 20x + 2x + 40
x² + 26x = x² + 22x + 40
4x = 40
x = 10
So the length of DO is 10 cm.