\(MP=\dfrac{2}{3}MC\)
=>\(\dfrac{CP}{CM}=\dfrac{1}{3}\)
=>\(S_{CNP}=\dfrac{1}{3}\cdot S_{CNM}\)
=>\(S_{CNM}=5\cdot3=15\left(cm^2\right)\)
Vì BN=2/3BC nên CN=1/3BC
=>\(S_{CNM}=\dfrac{1}{3}\cdot S_{MCB}\)
=>\(S_{MCB}=15\cdot3=45\left(cm^2\right)\)
Vì AM=1/4AB
nên \(BM=\dfrac{3}{4}AB\)
=>\(S_{MCB}=\dfrac{3}{4}\cdot S_{ABC}\)
=>\(S_{ABC}=\dfrac{4}{3}\cdot45=60\left(cm^2\right)\)
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