If it's maximization, the feasible region is going inwards from the corner points, while in minimization, the feasible region is the are going upwards from the corner points.

It is determined by the intersections of constraints boundaries it has in the problem's solution space or dots. 

it is determined by the intersection of constraints 

it is determined by the intersection of constraints 

It is determined by the intersection of the constraints

it is determined by the intersection of the constraints

it is determined by the intersection of constrains