Did you notice that all of the perpendicular bisectors meet in a single point? This point of concurrency is called the circumcenter of the triangle.
When the triangle is acute the circumcenter is inside the triangle. When one of the angles becomes a right angle, the circumcenter is at that vertex. As the angle becomes larger and the triangle is obtuse, the circumcenter is outside the triangle. If you didn't notice this relationship, go back and move one of the vertices of your triangle around until you see it.
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