Question

Answer 1

Ta có: MB=MC

=>\(S_{PMB}=S_{PMC};S_{NMB}=S_{NMC}\)

=>\(S_{PMB}-S_{NMB}=S_{PMC}-S_{NMC}\)

=>\(S_{PNB}=S_{PNC}\)

TA có: AN+NC=AC

=>\(NC=AC-AN=\frac45AC\)

=>\(AN=\frac14\times NC\)

=>\(S_{PAN}=\frac14\times S_{PNC}\)

=>\(S_{PAN}=\frac14\times S_{PNB}\)

=>\(S_{PNA}=\frac13\times S_{BAN}\)

TA có: \(AN=\frac15\times AC\)

=>\(S_{BAN}=\frac15\times S_{BAC}\)

=>\(S_{PNA}=\frac13\times\frac15\times S_{ABC}=\frac{1}{15}\times S_{ABC}\)