Răspuns:
Vezi desenul
Explicație:
[tex]BM = \frac{1}{2}\sqrt{2*AB^{2} + 2*BC^{2} - AC^{2}} \\\\BM = \frac{1}{2}\sqrt{2*9^{2} + 2*12^{2} - 15^{2}} \\\\BM = \frac{1}{2}\sqrt{2*81 + 2*144 - 225}\\\\BM = \frac{1}{2}\sqrt{162 + 288 - 225}\\\\BM = \frac{1}{2}\sqrt{225}\\\\BM = \frac{15}{2} \\\\BM = 7,5 cm[/tex]
