Answer:
The vertices of the rectangle is the same as the corner of each circle and it also has an equal distance. The center of the circle and the center of the rectangle is the same then the distance from the center to the vertex of the rectangle is the radius......
Not sure but I think it is 3. If you get it wrong I am so sorry.
Solve the inequality , find the max possible value for the variable.
3t + 1 < t + 12
2t < 11
t < 5.5
t_max = 5.5
For the second question just solve as two separate inequalities
4 +2 < x <= 7 + 2
6 <x <= 9
x in ]6, 9]