Given that ΔABC ~ ΔDEF and their areas are 64 cm2 and. 121 cm2 re

1.	Given that ΔABC ~ ΔDEF and their areas are 64 cm2 and. 121 cm2 respectively. If EF = 15.4 cm, then BC =(A) 2.11 cm (B) 21.1 cm (C) 1.21 cm(D) 11.2 cm
Answer» Correct option is (D) 11.2 cm \(\because\) \(\frac{ar(\triangle ABC)}{ar(\triangle DEF)}=(\frac{BC}{EF})^2\) \((\because\triangle ABC\sim\triangle DEF)\) \(\Rightarrow\) \(\frac{64}{121}=(\frac{BC}{15.4})^2\) \(\Rightarrow\) \(\frac{BC}{15.4}=\sqrt{\frac{64}{121}}=\frac{8}{11}\) \(\Rightarrow BC=\frac8{11}\times15.4\) \(=8\times1.4=11.2\,cm\) Correct option is: (D) 11.2 cm

Given that ΔABC ~ ΔDEF and their areas are 64 cm2 and. 121 cm2 respectively. If EF = 15.4 cm, then BC =(A) 2.11 cm (B) 21.1 cm (C) 1.21 cm(D) 11.2 cm

Answer»

Correct option is (D) 11.2 cm

\(\because\) \(\frac{ar(\triangle ABC)}{ar(\triangle DEF)}=(\frac{BC}{EF})^2\) \((\because\triangle ABC\sim\triangle DEF)\)

\(\Rightarrow\) \(\frac{64}{121}=(\frac{BC}{15.4})^2\)

\(\Rightarrow\) \(\frac{BC}{15.4}=\sqrt{\frac{64}{121}}=\frac{8}{11}\)

\(\Rightarrow BC=\frac8{11}\times15.4\)

\(=8\times1.4=11.2\,cm\)

Correct option is: (D) 11.2 cm