[tex]\text{Aflam cos B cu teorema cosinusului.}\\
AC^2=AB^2+BC^2-2\cdot AB\cdot BC\cdot \cos B\\
100=100+144-2\cdot 10\cdot 12\cdot \cos B\\
100=244-240\cdot \cos B\\
240\cdot \cos B=144\\
\cos B=\frac{144}{240}=\frac{3}{5}\\
\\
\sin^2B+\cos^2 B=1\\
\sin^2B+\frac{9}{25}=1\\
\sin^2B=\frac{16}{25}\\
\sin B=\frac{4}{5}\\
\text{Sper ca te-am ajutat.}[/tex]
