Question

Ko bt làm;-;

Answer 1

Sửa đề: MN cắt AB tại E

Ta có: CN=3xNA

=>\(S_{ENC}=3\times S_{ENA}=3\times9=27\left(\operatorname{cm}^2\right)\)

Ta có: MB=MC

=>\(S_{EMB}=S_{EMC};S_{NMB}=S_{NMC}\)

=>\(S_{EMB}-S_{NMB}=S_{EMC}-S_{NMC}\)

=>\(S_{ENB}=S_{ENC}\)

=>\(S_{ENB}=27\left(\operatorname{cm}^2\right)\)

=>\(S_{ENA}+S_{BAN}=27\)

=>\(S_{BAN}=27-9=18\left(\operatorname{cm}^2\right)\)

CA=CN+NA

=>CA=NA+3xNA=4xNA

=>\(S_{CAB}=4\times S_{BAN}=4\times18=72\left(\operatorname{cm}^2\right)\)