How would I solve this? In need of help quick. Thank you :)

Using the side-splitter theorem, daniel wrote a proportion for the segment formed by luke segment de. what is ec?

How to do this , and can some one explain

5, 6, 10 question: a. determine whether the side lengths form a triangle. (explain your reasoning) b. if it is a triangle, determine whether it is a right, acute, or obtuse triangle. (show your work)