Circular pen means you are going to use Area = Pi(r^2).
So 78.5 = pi(r^2). Divide by pi on both sides to get r^2 = 78.5/pi. Take the square root of that to get r or radius = approximately 4.99. If you need an exact answer then use

for the next part because you are not done yet.
Plug whatever R you use into the circumference formula of Circumference = 2(pi)(r).
If you use 4.99, you do 2(pi)(4.99) which is approximately 31.35. If you use the exact answer, you do 2(pi)(

) which gives you approximately 31.41.
Either way you'll need about 31 meters of chicken wire but the 31.40796 or ~31.41 is closer to the exact answer.
Yes. all the friends will get at least one cup of juice
To minimize the cost, we take the straight distance from the refinery to the other side of the river as 2 km. Also, the 7 km will be the distance that has to be traveled by the pipeline in land. The total cost, C, is therefore,
total cost = (2 km)($800,000/km) + (7 km)($400,000 /km)
total cost = $4,400,000
Thus, the total cost of the pipeline is approximately $4,400,000.00.
Answer:
d/t
D= Distance
T= Time
Step-by-step explanation: