The second day of the first volume of mathematics congruent triangles problem! ! ! ! ! ! ! ! ! ! ! ! ! ! !
As shown in the figure, in △ABC, BD is the bisector of △ ABC. Take a point E outside △ABC so that ∠EAB=∠ACB, AE=DC, line segment ED intersects with line segment AB, and the intersection point is marked as K, and E is marked as EI⊥AB in I. What is the size relationship between straight line EK and DK? And explain why.