Justin is using the figure shown below to prove Pythagorean Theorem using triangle similarity.

In the given triangle ABC, angle A is 90o and segment AD is perpendicular to segment BC.
Which of these could be a step to prove that BC2= BA2 + CA2?
Answer
Segment AD : segment CD = segment BD : segment AD, since triangle ADB is similar to triangle CDA.
Segment BD : segment BA = segment BA : segment CA, since triangle ADB is similar to triangle CDA.
Segment BC : segment BA = segment BA : segment BD, since triangle BCA is similar to triangle BAD.
Segment BA : segment DA = segment AC :

Question

Justin is using the figure shown below to prove Pythagorean Theorem using triangle similarity. 

In the given triangle ABC, angle A is 90o and segment AD is perpendicular to segment BC.
Which of these could be a step to prove that BC2= BA2 + CA2?
Answer
Segment AD : segment CD = segment BD : segment AD,  since triangle ADB is similar to triangle CDA.
Segment BD : segment BA = segment BA : segment CA,  since triangle ADB is similar to triangle CDA.
Segment BC : segment BA = segment BA : segment BD,  since triangle BCA is similar to triangle BAD.
Segment BA : segment DA = segment AC :