It will be distort for heating in the process of cutting board
so the parts of cutting off from the board couldn' t be used any more. We take rectangle cutting from the material which contained the needed parts
and make it contain the minimal hearting distort by doing that. This paper solves the problem how to certain a minimal circumscribed rectangle of arbitrary polygon. Meanwhile an algorithm for it is presented
and its time complexities are given
that is
O(k^2) (k is the number of the vertices of the polygon).