Respuesta :

sina+cosa=1.2
Squaring on both sides we get,
(Sina)^2+2sina.cosa+(cosa)^2=1.44
(sina)^2+(cosa)^2+2sina.cosa=1.44
1+2sina.cosa=1.44
2sina.cosa=1.44-1
2sina.cosa=0.44
sina.cosa=0.22