The triangular AED and the triangular BCD are congruent triangles,

Because the angle C=90 degrees and the angle AED=90 degrees.

So DE is vertical AB.

② because AD=BD,

So the triangle ADB is an isosceles triangle,

Because DE is perpendicular to AB,

So point e is the midpoint of AB,

So AE=BE.

Because AE=BC,

So BE=BC,

Because de =DC,

So the triangular bed and the triangular BCD are congruent triangles.

So angle EBD= angle CBD

So BD bisects the angle ABC