P=(4+5+6)/2=15/2=7,5
\(S=\sqrt{7.5\left(7.5-4\right)\left(7.5-5\right)\left(7.5-6\right)}=\dfrac{9\sqrt{35}}{4}\)
\(\dfrac{1}{2}\cdot h_A\cdot4=\dfrac{9\sqrt{35}}{4}\)
=>\(h_A=\dfrac{9\sqrt{35}}{8}\)
\(\dfrac{1}{2}\cdot h_B\cdot5=\dfrac{9\sqrt{35}}{4}\)
=>\(h_B=\dfrac{9\sqrt{35}}{10}\)
\(\dfrac{1}{2}\cdot h_C\cdot6=\dfrac{9\sqrt{35}}{4}\)
=>\(h_C=\dfrac{3\sqrt{35}}{4}\)