9. If two people in balloons were released to the same elevation as Felix and could still see each other, how many radians would be between them? (1 point)
10. How many radians are in a complete circle? (0.5 points)
11. How many Felixes would it take to cover the circumference of the Earth so that one Felix could see the next, could see the next, see the next, and so on, and so on? (1 point)
12. If Felix were to look in a circle around his balloon, how many square miles of the Earth is he able to see? (1 point)
13. What is the formula to find surface area of a sphere? (0.5 points)
14. What is the surface area of the Earth in square miles? (1 point)
15. How many Felixes would it take to cover the entire surface of the Earth, so that one Felix could see the next, see the next, and so on, and so on. (1 point)