C4. The "Circle through 3 points" tool
Draw the circumcentre of the triangle
The circumcentre of a triangle is the point of intersection of the perpendicular bisectors of the sides, allowing to draw the triangle’s circumcircle. With GeoGebra you can draw the circumscribed circle first and then the circumcentre.
1st. Activate the "Circle through 3 points" tool 
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2nd. Click on the three vertices of the triangle and you will get the circumcircle "d".
3rd. Activate the "Midpoint or centre" tool 
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4th. Click on the circumscribed circle "d".
5th. Activate the "Move" tool 
and name "Circumcenter" at the centre point of the circumference.
The two curved arrows located in the upper right corner of the Graphics View allow you to reset the activity.
If the activity is correct, you will get 10 points automatically.
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2nd. Click on the three vertices of the triangle and you will get the circumcircle "d".
3rd. Activate the "Midpoint or centre" tool .
4th. Click on the circumscribed circle "d".
5th. Activate the "Move" tool and name "Circumcenter" at the centre point of the circumference.
The two curved arrows located in the upper right corner of the Graphics View allow you to reset the activity.
If the activity is correct, you will get 10 points automatically.