Question

Consider the diagram. What is the length of segment AB?

Answer 1

we know that

A median of a triangle is a line segment joining a vertex to the midpoint of the opposing side, bisecting it.

In this problem the line DB is a median of triangle ADC

The line DB is also the altitude of a triangle ADC, because is perpendicular to the side AC

so

AB=BC

we have that

$BC=9\ units$

therefore

$AB=9\ units$

the answer is the option

$9$

Answer 2

B. 9 I think because it looks like it is bisected in the middle to cut into two equal parts. Please correct me if I am wrong. Thanks.