Step-by-step explanation:
ED is greater than BC
the line from B to ED ^ (which i drew ) the point it touches ED name it X. so EX will be 2 ( ED-BC)(6-4).
then u have a triangle. EX, XB and EB.
you have length of EX(2) and u have hypotenuse. so u can calculate XB using Pythagoras theorem.
15.1²=2²+XB²
15.1²-2²=XB²
224.01=XB²
XB=14.97
since XB and DC are parallel ( a rectangle is forming XBCD) so DC is also 14.97
