Question

Sa se afle masura unghiului A stiind ca: AC^2 +AB^2 + AB x AC =BC^2

Answer 1

 

$\displaystyle\\\text{Aplicam teorema lui Pitagora generalizata,}\\\text{care se mai numeste teorema cosinusului.}\\\\BC^2=AC^2 +AB^2 -2cos(A)\times AB \times AC\\\\\text{Enuntul tau este:}\\\\BC^2=AC^2 +AB^2 + AB \times AC\\\\\implies~~-2cos(A)=1\\\\\implies~~cos(A)=-\frac{1}{2}\\\\\implies~~\boxed{\bf m(\sphericalangle A)=120^o}$