Answer:
2.9
Step-by-step explanation:
It just is
Answer:

Step-by-step explanation:
Use the circle equation, 
Plug in the center and radius:

Simplify:

So, the equation is 
36:21 in simplest form is 12:7, because 3 goes into both 36 and 21. Simplifying ratios is essentially the same thing as simplifying fractions. Once we have 12:7, we can't reduce any further, because 7 is prime.
Hope this helps!
Answer:
11.1714
Step-by-step explanation:
Just use a calculator! :)