Try to understand this. Hope this help. Answer for 2 only.
1.33333
Step-by-step explanation:
Don't worry it checks out.
....................................3.....................................
Answer:
No
Step-by-step explanation:
The equation of a circle with center (a,b) and radius r is given as:

If a given point (x,y) does not lie on this circle, it will not satisfy its equation.
This means the distance from the point to the center is not equal to the radius.
It is either less or greater than the radius.
Hence you cannot write the equation of the circle.