i have attached a file you can see it from there.
Answer:

Step-by-step explanation:
CD is perpendicular to AB
If any radius or diameter is perpendicular to any chord of a circle, then it bisects that chord.
Mean, AB= BE = 12
So, AB = 2(BE)
2(12)= 24
so your answer will be 24

hope it helps..
have a great day!!
You have to find the angle for it try it!!!!!!!!!!