a) Ta có:
SΔBMC = $\frac{1}{2}$ x MK x BC
thay số:
$\frac{1}{2}$ x 8 x BC = 96
⇒ BC = $\frac{96×2}{8}$ = 24 (cm)
b) Vì MK = $\frac{2}{3}$ AH
⇒ AH = $\frac{3×MK}{2}$ = $\frac{3×8}{2}$ = 12 (cm)
⇒ SΔABC = $\frac{1}{2}$ x AH x BC = $\frac{1}{2}$ x 12 x 24 = 144 (cm²)
Mà SΔBMC = 96 (cm²)
⇒ SΔABC > SΔBMC ( 144 > 96)
