In this paper we consider some properties of. bisector of interior angle(theorem 1) and exterior angle(theorem 2) in triangle by using analogy. As a result of analyzing various mathematics textbooks we have known that they focused not on relation between two theorems, but on describing two theorems. We have seen that theorem 2 is able to be inferred from theorem 1 by using analogy. After proving theorem 1 by some methods we analyze proof process, extract proof ideas, and analogize some ideas for proving theorem 2. From this we are able to find relationships between theorem 1 and 2.