Need a lot of help over multiple questions. Plenty of medals are involved.

Question

batman31 · Answer

I have to fix incorrect answers i gave, but I still don´t get the concepts.

anonymous · Answer

What are your questions? I'll see if I can answer any :3

batman31 · Answer

I´m trying to fight my screenshot app atm, give me a sec.

batman31 · Answer

http://prntscr.com/7d77i2 is the first one. I also have to fill t his out for it The answer you initially gave: Why you thought this was the correct answer (show work, if necessary): The answer you have changed it to: Why this is the correct answer (you MUST show all work for how you found this answer and explain your thinking.)

anonymous · Answer

as it says below use pythagorean theorem 
$$a^2+b^2=c^2$$
and when you solve for CB you multiply that by two and get the length of AB

anonymous · Answer

OB=28
OC=9
$$CB^2+9^2=28^2$$
Find CB

anonymous · Answer

@BATMAN31

Can you solve for CB from here ?