Logik och Geometri
Femhörningens vinkelsumma: https://www.geogebra.org/m/pxue2m7h
Pythagoras sats: https://www.geogebra.org/m/dBu3hnqx
Randvinkel: https://www.geogebra.org/m/jmabzrty
Vinklar vid parallella linjer: https://www.geogebra.org/m/ztgesgr6
Proof without words (engelsk bok): https://www.geogebra.org/m/jFFERBdd
Quadrilaterals (engelsk bok): https://www.geogebra.org/m/GFwZ5qdf
Surface area and volume (engelsk bok): https://www.geogebra.org/m/s7TznqSP