Ответы и объяснения

2014-02-23T10:51:47+00:00
AB/DE = 9/3 = 3;
BC/EF = 12/4 = 3;
AC/DF = 18/6 = 3.
⇒ AB/DE = BC/EF = AC/DF⇒ ΔABC подобен ΔDEF.
AB параллельно DEю