Hands on (3)

Circumcircle of a Triangle Construction

Construct the circumcircle of a triangle by following the construction steps below.  

Instructions

Select tool Polygon. Create an arbitrary triangle ABC by clicking three times in the Graphics View. Close the triangle by selecting the first point A again.

Activate tool Perpendicular Bisector.
Construct the Perpendicular Bisector for two of the edges of the triangle by successively selecting the segments.
Hint: You can find this tool in the Special Lines Toolbox (fourth Toolbox from the left).

Create intersection point D of the two the line bisectors.
Hint: Successively select the two line bisectors, or click directly on the intersection point.

Construct a circle with center D through one of the vertices of triangle ABC.
Hint: First, select point D, then, for example, point A.

Select the Move tool and drag the vertices of the triangle in order to check if your construction is correct.