Answer:
≈ 5.36
Step-by-step explanation:
If we have a triangle in which the angle measure of it being broken down are the same, that means that the legs in which the angle measures are the same will have the same length.
If we already know that DE ≈ 9.28, then we can subtract this from 20 and divide by two to get BD, which is equal to EC.
However, I'm not 100% sure about this answer.
Hope this helped (and I hope I'm right)