[tex]BC^{2}=AB^{2} + AC^{2} -2AB.AC cos\ \textless \ A [/tex]
[tex] BC^{2}=144+225-2.12.15. \frac{1}{2}=549 \\ BC=3 \sqrt{61} [/tex]
A=[tex] \frac{AB.AC.sin\ \textless \ A}{2} =45 \sqrt{3} [/tex]
[tex]h_{a} = \frac{2.45 \sqrt{3} }{3 \sqrt{61} } [/tex]
[tex]h_{b} = \frac{2.45 \sqrt{3} }{15} [/tex]
[tex] h_{c} = \frac{2.45 \sqrt{3} }{12} [/tex]
