Hello, kingkaisai2!
The problem is badly worded ... it makes no sense.
I'll take a guess at what you meant . . .
Also, in all your problems, unless the inequality is
. . there is no solution.
Are you sure it's "less than"?
Find the least possible value of such that
Describe in geometrical terms.
We have: .
This is the set of points within 2 units of
This is the set of points in or on the circle
. . with center and radius Code:

* * * 
* * 
* * 
* *
_ 
* (2,√3) *
* C* *
* \ *
\ 
* \ *
* o 
**+
* * * O

The point with the least magnitude
. . is the intersection of the circle and the line
The line has the equation: .
The circle has the equation: .
Find their intersections and take the rightmost point.