[Risolto] matee

B, C = angoli acuti complementari 

sin C = cos B = 3/9 = 1/3

sin B = radice [1 - (1/3)²] = (2/3)* radice (2)

Quindi: 

cos(C) = sin B = (2/3)* radice (2)

tan(B) = sin B / cos B = 2* radice (2)