Measurement of angle with a protactor

How to use a protactor[br]An old file of my site http://dmentrard.free.fr/GEOGEBRA/Maths/Elementaire/Elementaire.htm but the link was remaining on the ancien site of Geogebra ( www.geogebra.at/webstart/geogebra.jar)[br]Now update in 4

Information: Measurement of angle with a protactor