WEBGRAFIA:

http://www.aulafacil.com/cursos/l10047/ciencia/fisica/fisica-general-i-notaciones-cientificas-funciones-trigonometricas/funciones-trigonometricas

http://hotmath.com/hotmath_help/spanish/topics/law-of-cosines.html

https://sites.google.com/site/timesolar/teoremapitagoras/leysenos

https://www.youtube.com/