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If the perimeters of two similar triangles ABC and DEF are 75 cm and 40 cm respectively, and if BC is 15 cm, then the length of EF is:
6 cm
10 cm
12 cm
8 cm
8 cm
Finding Corresponding Side Length from Ratio of Perimeters of Similar Triangles
△ABC∼△DEF, Perimeter of △ABC=75 cm, Perimeter of △DEF=40 cm, BC=15 cm
Perimeter Ratio Property
For two similar triangles, the ratio of their perimeters equals the ratio of any pair of corresponding sides: Perimeter(△DEF)Perimeter(△ABC)=EFBC
4075=EF15
Calculate Side EF
815=EF15⟹EF=8 cm
EF=8 cm
Option D is correct — 8 cm