C2. The "Circle with Centre and Radius" tool
Draw a circumference centered on point "A" with 2 radio units
You will be taken to create another dynamic text. A text is formed by an expression enclosed in double quotes. They have a very interesting property, you can join numbers in the texts with the sum.
1st. Activate the "Circumferencia donadas el centro y el radio"
tool. A radius call dialog window appears.
2nd. Type 2 and then the "OK" button. The circumference will appear with 2 radio units.
3rd. Activate the "Move" 
tool, and in the "Input:" zone, enter the command to know the area of the circumference. t1 = FormulaText("Area =" + Area(c) + "cm^2")
The first sum, "Area =", is enclosed in quotation marks, is a static text that indicates the name of the property, the second sum, Area(c), calculates the property, is the dynamic part of the text and the third sum, "cm^2" is also a static text that indicates the unit of measurement. The circumflex accent, ^, is used to indicate in GeoGebra that behind there is an exponent.
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.
tool. A radius call dialog window appears.
2nd. Type 2 and then the "OK" button. The circumference will appear with 2 radio units.
3rd. Activate the "Move" tool, and in the "Input:" zone, enter the command to know the area of the circumference. t1 = FormulaText("Area =" + Area(c) + "cm^2")
The first sum, "Area =", is enclosed in quotation marks, is a static text that indicates the name of the property, the second sum, Area(c), calculates the property, is the dynamic part of the text and the third sum, "cm^2" is also a static text that indicates the unit of measurement. The circumflex accent, ^, is used to indicate in GeoGebra that behind there is an exponent.
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.