Translation of [url]33112 Introduce to Cosine and Tangent[/url] by alexchik (http://www.geogebratube.org/user/profile/id/4422 ).
[b]GeoGebra Institute of Hong Kong[/b]
https://sites.google.com/site/hkgeogebra/
http://www.facebook.com/hkggb
email: [b]geogebra.hk@gmail.com[/b]
