Perpendicular lines and midpoints of triangles

Topic:
Triangles
Below is Triangle ABC inscribed in a circle. The lines are the perpendicular bisectors of the sides of the triangle. D is the intersection of the three perpendicular bisectors.
Use the tools to confirm that: 1) Each line is perpendicular, and 2) Each line goes through the midpoint. Move the vertices of ABC around and explore how point D relates to the circle.