Last question! need help on confirming answer!

Question

anonymous · Answer

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?

anonymous · Answer

attachment

anonymous · Answer

Segment AD : segment CD = segment BD : segment AD,  since triangle ADB is similar to triangle CDA.
    is it this one?	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 : segment BA,  since triangle BCA is similar to triangle BAD.

anonymous · Answer

is seg:bd : seg: ba = seg: ba : seg:ca?

zepp · Answer

BC2= BA2 + CA2

That's the pythagorean's theorem!

anonymous · Answer

yes

i've seen where your good on proofs so I asked you for help

zepp · Answer

I've never proved this theorem by using triangles :| Lemme check.

zepp · Answer

Yes, your choice is right :)

anonymous · Answer

YES! thanks

zepp · Answer

Then you have to cross multiply the ratios, add them up and simplify :)