Question

Answer 1

Bài 5:

a: Xét ΔABC và ΔMNP có 

\(\dfrac{AB}{MN}=\dfrac{AC}{MP}=\dfrac{BC}{NP}\left(\dfrac{2}{4}=\dfrac{2.5}{5}=\dfrac{3.5}{7}=\dfrac{1}{2}\right)\)

=>ΔABC~ΔMNP

b: ΔABC~ΔMNP

=>\(\dfrac{C_{ABC}}{C_{MNP}}=\dfrac{AB}{MN}=\dfrac{2}{4}=\dfrac{1}{2}\)

Bài 6:

a: Xét ΔAFE và ΔMNG có

\(\dfrac{AF}{MN}=\dfrac{FE}{NG}=\dfrac{AE}{MG}\left(\dfrac{b}{3b}=\dfrac{a}{3a}=\dfrac{c}{3c}=\dfrac{1}{3}\right)\)

=>ΔAFE~ΔMNG

b: Ta có; ΔAFE~ΔMNG

=>\(\dfrac{C_{AFE}}{C_{MNG}}=\dfrac{AF}{MN}=\dfrac{1}{3}\)

=>\(C_{MNG}=3\cdot15=45\left(cm\right)\)