Answer:
Part a) ABD and CDE are similar by AA Similarity Postulate
Part b) [tex]x=18\ units[/tex]
Step-by-step explanation:
we know that
If two figures are similar, then the ratio of its corresponding sides is equal and its corresponding angles are congruent
In this figure Triangles ABD and CDE are similar by AA Similarity Postulate
[tex]\frac{AB}{ED}=\frac{BD}{CD}[/tex]
substitute the values
[tex]\frac{x}{6}=\frac{12}{4}[/tex]
[tex]x=6*12/4=18\ units[/tex]
