There isn't enough information to answer this, what is the given area or perimeter?
Answer:
7 km
Step-by-step explanation:
Substitute:
The equation for area of a semi-circle is 
A = 
76.97 = 
Multiply by 2 on both sides:
2(76.97) = (
)2
153.94 = 
Divide by pi on both sides:
153.94 = 
/pi /pi
49.03 ≈ 
Find the square root:

7 = r
Answer:
7/12
Step-by-step explanation:
3/12=1/4
2 1/4=9/4
8/12=2/3
1 2/3=5/3
---------------
9/4-5/3=27/12-20/12=7/12