# Circumcircle of a triangle (Soft Construction)

- Author:
- Anthony OR 柯志明

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*Drag the three vertices of the triangle to change its shape.*) Drag the blue point to A. Drag the centre (the red point) to different positions at which the circle also passes through B. Observe the marks of these positions. What are their characteristic? What is the charateristic of the positions of the centre at which the circle passes through A and C? How to draw the circle which passes thorough A, B and C?Anthony Or. GeoGebra Institute of Hong Kong.