How do you find the equation of the top half of a circle?

Related questions

1. Can a circle be a function?
2. What is the equation for half a circle?
3. Why does PI exist?
4. What is a radius of a circle?
5. How do you find the equation of a circle?
6. How do you find the Directrix?
7. How do you find the equation of a quarter of a circle?
8. Why does PI go on forever?
9. How much is a diameter of a circle?
10. How do you find the points of a circle?

Tags

1. #equations
2. #positive
3. #general
4. #semicircle
5. #square
6. #upper
7. #describes
8. #solved
9. #lower
10. #result
11. #negative
12. #equation