What is the length of chord FL in A below?

Answer:
D.
Step-by-step explanation:
If you would rotate RN until R meets L it would exactly overlap with FL. So RN=FL.
Answer:
13.52
Step-by-step explanation:
If the distance between A and FL is the same between A and RN, you know that the angle between then is the same (90°). The two lines have the same lenght.
So, if RN is 13.52, FL is 13.52 too.